The following dispatch is based on information arriving from Poland.

More than 1,100 miners are continuing their underground strike at the Ziemont mine in the southern region of Silesia, and another 1,742 are occupying a mine in nearby Piast, Polish government officials said yesterday in a Warsaw news conference that also contained the first official acknowledgment that Solidarity leader Lech Walesa is under detention.

Government spokesman Jerzy Urban confirmed that Walesa is being held in Warsaw and has been visited by his wife and children along with a priest who celebrated Sunday mass for him. Walesa has access to radio, television and newspapers, the spokesman said. There was no independent confirmation of the statement.

Urban said Walesa will be released "as soon as the situation in the country allows."

[In Moscow, the Soviet news agency Tass reported that thousands of workers have barricaded themselves inside the Katowice steel mill, where "militants from Solidarity, in a clear act of blackmail, threaten to explode the central furnaces."]

[In Washington, the State Department cited fragmentary reports from Poland suggesting "continuing resistance in some areas and continued use of force in some instances" against striking workers. Spokesman Dean Fischer said strikes were ongoing "in perhaps as many as 20 coal mines" in Silesia and cited Western and Polish eyewitness reports that strikers remained in the Lenin steel mill near Krakow despite two attempts by security forces to dislodge them.]

With internal communications in Poland still cut off and Western correspondents limited to Warsaw, it continued to be impossible for reporters to confirm independently information from outside the capital.

At the news conference yesterday, officials said approximately 5,000 people had been interned under the nine-day-old martial-law government. Both Urban and Wieslaw Gornicki, an adviser to the martial-law chief and premier, Gen. Wojciech Jaruzelski, denied persistent independent reports that the number of those arrested is several times that figure -- perhaps reaching as high as 49,000.

The spokesmen claimed that the only deaths associated with the imposition of martial law were those of seven miners the government said last week had died when police moved in to break up the occupation of a mine at Wujek. Independent sources have put the number of deaths much higher.

A Foreign Ministry official delivered a stinging, bitter attack on the former Polish ambassador to the United States, Romuald Spasowski, who was granted political asylum Sunday by President Reagan.

The official called Spasowski's act "desertion" and "an act of treason against the state," and said that the military prosecutor's office would start criminal proceedings against him.

He charged that Spasowski had been suffering from "psychological depression" that led him to slander Poland and to mouth the views of his antisocialist American hosts. "For Judas' silver," the official said, Spasowski "has abandoned his fatherland."

[In Rome, Western news agencies reported last night the arrival of Bishop Bronislaw Dabrowski, secretary of the Polish bishops' conference, for talks with Pope John Paul II. Dabrowski is believed to be the first high-ranking church official to be allowed to leave Poland since the military takeover Dec. 13. His trip to the Vatican coincides with the arrival in Poland yesterday of Vatican emissary Archbishop Luigi Poggi, who was dispatched by the pope to reestablish contact with the Polish Catholic Church.]

Poggi said on his arrival Sunday that he was hoping to meet representatives of the military authorities as well as Polish bishops. Poggi, who is not known to have communicated with the Vatican the results of his talks yet, said Sunday night that he carried a message from the pope, with whom he met last Friday. Poggi said the pope expressed his grave concern at the fate of his homeland and his hope that the situation could be resolved peaceably.

Although officials at the government press conference in Warsaw painted a humane picture of conditions for those detained, church sources said yesterday that a volunteer effort to deliver packages of warm clothing to prisoners has been frustrated by government foot-dragging in granting permission for entrance to the detention centers. They said that only 50 packages had been delivered so far, while 500 others are being held up.

Church sources also disclosed in Warsaw that priests had conducted masses at the mines on strike in Silesia. The sources said they believed the government's strategy was to allow the miners to stay underground until they came out on their own accord because of hunger, cold weather or lack of light.

The sources, close to the Polish primate, Archbishop Jozef Glemp, said negotiations with the ruling military council were in progress and that, despite a generally bleak outlook, there were some encouraging signs. The nature of the negotiations was unclear, but they are believed to involve the church's demand for a quick release of detainees in return for its support for efforts to calm public opinion.

Although military spokesmen inside Poland continued to stress that the situation "is getting more and more stable," Polish news dispatches and broadcasts made a number of detailed references to work stoppages and potential violence.

Referring to the mine occupations in Silesia, Radio Warsaw said that "major efforts are being made to settle this dangerous conflict through persuasion, without using force." The radio said there had been no casualties at the Ziemowit mine, or at the Piast coal mine, 18 miles southwest of Katowice, where it said 1,742 miners were continuing a strike action.

The radio broadcast the text of what it said were letters sent by the directors of the two mines to workers, "personally guaranteeing that no worker forced to strike" will be punished.

Pressing the drive against active dissent, the prosecutor general yesterday announced "activities designed to stave off protest and strike actions." The prosecutor's office also announced "further summary legal actions" against Solidarity activists charged with organizing strikes and sit-ins, disrupting production by sabotaging equipment, attempts to incite soldiers to disobey orders and distributing leaflets encouraging workers to strike. The communique, carried by the official Polish news agency PAP, indicated widespread resistance to martial law, particularly through Dec. 18.

At the same time, the government has made an effort at conciliatory gestures toward the Solidarity "worker masses." A Tass report quoted K. Bogaciewicz, a member of the Solidarity presidium in Rzeszow, saying that his regional union board "was directed at political activities such as spreading misleading propaganda. More often than not, the workers did not even want to read it. They were preoccupied with crisis and anarchy."

The appeal to reason within the Solidarity rank and file has been coupled with repeated promises that the martial-law authorities do not intend "a return to before August 1980," when Solidarity was founded, and a pledge to continue the process of "national renewal." The promises, however, have referred only to national economic reforms planned under the new system, and have made no mention of political reforms allowing the kind of freedoms of expression and political activism that were part of the original accords between Solidarity and the government.

[In the same vein, Wieslaw Gornicka, a special assistant to Jaruzelski, said in a CBS interview broadcast Sunday night, "I cannot imagine, envision, Poland after the state of war is lifted without Solidarity." He mentioned three conditions for the repeal of martial law, including "no more disorders," indications that "the gears are starting working again" in the country's devastated economy and assurances that there will be no "renewal of . . . counterrevolutionary activities."]

The government also has attempted to bolster the position of Poland's Communist Party in reports by official media over the past several days, moving to counter suggestions that the party's role has been undermined by the nine-day-old military crackdown and to mobilize a broader popular "sense of responsibility."

Interviews with party officials, broadcast over Radio Warsaw and reprinted in the Polish media, spoke of a "grass-roots initiative" within the party, "spontaneously arising from the feeling of belonging to the party, of being a Communist, and a sense of responsibility to one's own class, one's own nation."

"The party staff cells have also become more active," Communist Party Central Committee Secretary Marian Orzechowski said in an interview with the Army newspaper Zolnierz Wolnosci. "They have developed instructional and coordinating activity equipping the people with arguments."

Orzechowski added: "People must have hope for today and tomorrow. For today that they will survive; that the winter will be calm without shocks and hunger." For the future, Orzechowksi cited the ruling military council's position that "there can be no question of a return to the pre-August 1980 situation".

The official media reported problems of transporting supplies and indicated shortages in areas including Gdansk, the birthplace of Solidarity. Military authorities also appealed to private farmers, saying that the sale of agricultural produce has become "a patriotic duty." The appeal followed reports even before the military crackdown that farmers have been withholding their goods.

Official government and military sources yesterday spoke of possible relaxation of curbs on civil liberties and held out the more immediate prospect of certain economic reforms. The only concrete measure announced yesterday was an easing of travel restrictions for "traditional Christmas visits."

In an interview with the Polish party newspaper, Trybuna Ludu, Gen. Mieczyslaw Debicki, a member of the ruling military council, raised the prospect of martial law being repealed in areas of Poland "where the situation has improved decisively." He also mentioned government efforts to implement economic reforms including "new supply prices and reformed principles of taxes."

In a hard-line twist, however, he also said that Poles between the ages of 16 and 60 could be called up at any time by local authorities for any tasks they deemed suitable.

On the food supply front, Radio Warsaw quoted a party official as saying that "the difficult food situation is still continuing" and thanking Soviet authorities for their "especially valuable" help.

News agencies reported these other developments yesterday:

In New York, the International Longshoremen's Association announced a boycott of shipments bound for or originating from Poland at eastern and Gulf Coast ports, to support Solidarity.

In Geneva, the International Committee of the Red Cross said a Red Cross mission arrived in Warsaw Sunday in hopes of talks with Red Cross and government officials.