The country's leading Communist Party daily today strongly attacked a campaign of underground resistance that is developing in Poland.

Coming after a weekend of public protest against the martial-law regime, the official blasts in Trybuna Ludu were the most extensive attack so far against acts of dissent. Polish authorities have been reluctant to concede that such actions have much significance.

But continued acts of protest, including the spreading of underground leaflets and efforts to conspire against martial-law authorities, all in defiance of reinforced security measures and calculated efforts to intimidate the public, appear to have moved officials to intensify propaganda against the dissenters.

At the same time, authorities today relaxed extra restrictions that had been placed on Gdansk after a demonstration there Jan. 30. Bans on intercity telephone service and the use of private vehicles were lifted and the curfew pushed back to 10 p.m. But similar bans and an early curfew went into effect today in Poznan, where nearly 200 persons were arrested in a protest Saturday.

"News about circulation of antistate leaflets has come from certain parts of the country," acknowledged Marian Kuszewski of Trybuna Ludu in one article today. "Here and there attempts are being made to suggest forming conspiracies to secondary school pupils and to organize provocations against workers."

The reference to students reflected official concern about the large involvement of youths in recent street demonstrations in Poznan and Gdansk. The Poznan protest was said by the authorities to have been incited by leaflets urging people to demonstrate on Feb. 13, the two-month anniversary of the imposition of martial law.

"It has not been enough for the authors of these leaflets to call for passivity at work," Kuszewski went on. "They now begin to call for conspiracy against the state power. Again they are fanning adventurist moods. They set up dates for confrontation.

"Threats begin to appear" such as " 'Death to the red.' And assurances like, 'It will come to the bloody civil war.'

"But these have not been large-scale phenomena," Kuszewski added. "On the contrary, they are of an incidental, local character unaccompanied by discernible social repercussions. They bear no resemblance to what had taken place before Dec. 13. But this is not to say that they can go unnoticed or be taken lightly."

Trybuna Ludu also appeared to lash out at intellectual and particularly Catholic church sources who, increasingly frustrated by the slow relaxation of martial-law regulations and the lack of positive action on promised reforms, have spoken out more critically against the authorities.

"There are signals arousing astonishment that certain representatives of the clergy are making provocative statements and inciting political gestures," Kuszewski wrote. "Do they really know what they are doing?"

In another article, Norbert Michta, a journalist close to the party's hard-line faction, said that political agitation in Poland was still the work of those same dissident groups--the Committee for Social Self-Defense (KOR) and the Confederation for an Independent Poland (KPN)--that are responsible, in the official view, for taking over and manipulating Solidarity to the union's downfall.

"Unfortunately, not all of them have given up their political aspirations," Michta wrote. "Ignoring the realities, certain groups of counterrevolutionaries . . . of KOR, KPN and Solidarity, blinded by hatred and fury, are circulating leaflets with slandering and inciting contents. They are calling for conspiracy and even terrorist and revanchist acts, are attacking the Military Council of National Salvation, and are trying to antagonize the society against the armed forces."

While coping with demonstrating crowds seems to have proved little more than a nuisance for Poland's military rulers, the possible rise of terrorism in the country presents a considerably more chilling prospect. An organized terrorist campaign was last seen in Poland in the late 1940s as the Communists were first assuming control.

A 13-pound bomb found and defused in the western city of Lublin Saturday still has not been claimed or officially blamed on anyone. But the device suggested that Poland's fledgling underground groups may have means enough in the future to perpetrate substantial violence.

Announcement of both the Poznan and Lublin incidents was delayed a day. Their official disclosure late yesterday afternoon came after the telex center used by foreign correspondents here was closed and at the end of a tense weekend during which protests had been anticipated.

The delay may have been a result of official concern that if the news had been released during the weekend, it could have set off other disturbances.

Eyewitness reports reaching Warsaw today from Poznan said the demonstration began in the afternoon when a large crowd gathered around the monument in the city's center commemorating the bloody workers' uprising there in 1956.

Some people chanted Solidarity slogans. Police, wearing face- and arm-shields and armed with long truncheons, sought to block people from laying flowers at the monument, arresting those who tried to do so. Martial-law regulations prohibit protest demonstrations or large public gatherings.

Another group of demonstrators carrying lighted candles was reported to have returned to the monument area on Saturday evening.

In a further show of opposition in Poznan, bus stops, walkways and other public areas in the city were said to be littered with shredded copies of official newspapers.