Activists of Poland's suspended Solidarity trade union announced the establishment of an underground leadership today and called for a symbolic nationwide protest strike next month.

According to clandestine bulletins distributed to Western correspondents here, the new body met for the first time a week ago. Calling itself Solidarity's Provisional Coordinating Commission, it is made up of four senior union officials, representing different parts of the country, who have escaped detention following the imposition of martial law in December.

News of the formation of the provisional leadership coincided with the release of hundreds of Solidarity supporters from internment camps around the country. The official press devoted big coverage to the latest relaxation in martial law, treating it as evidence that life in Poland is returning to normal.

Talking to Western reporters outside an internment camp near Warsaw, released Solidarity activists said they had not changed their opinions as a result of their time in detention. They said they would continue to fight for the union's reinstatement.

The release of the internees was welcomed by Poland's Roman Catholic primate, Archbishop Jozef Glemp, who returned here today after meeting with Pope John Paul II in the Vatican. Glemp described the release as "a positive step" toward the rescheduling of the pope's visit, which, the archbishop announced in Rome, would almost certainly not take place in August as expected in view of martial law.

The easing of the martial-law regulations, including the lifting of the nighttime curfew on Sunday, has been presented by officials as a conciliatory gesture. Since 2,000 Solidarity activists are still in detention, however, it is thought unlikely to lead to any dramatic rapprochement.

In its statement released today, the Provisional Coordinating Commission said the only conditions for the holding of negotiations were the release of all internees and an amnesty for everybody convicted of crimes under martial law. This marks a softening from previous Solidarity demands, but it is still considerably farther than the authorities are prepared to go.

The commission includes three of Solidarity's best known leaders: Zbigniew Bujak, the chairman of the union's Warsaw branch; Wladyslaw Frasyniuk, the chairman of the Wroclaw branch, and Bogdan Lis, who was one of the organizers of the strikes in Gdansk in August 1980 that gave birth to an independent union. The fourth member of the commission is a local union leader from Krakow, Wladyslaw Hardek.

The most important region not represented on the new body is Katowice, the center of Poland's mining industry. Communications with Solidarity members in the Katowice region, formerly a union stronghold, were severely disrupted as a result of the military crackdown and tight police surveillance.

While underground bodies claiming to represent Solidarity have released statements before, this is the first time that nationally known union leaders have lent their names to such an initiative. The four men said they would be coordinating union activities until Solidarity's full national commission under Lech Walesa was able to resume its work. Walesa remains confined.

The first decree issued by the provisional leadership, dated April 22, called on all factories throughout Poland to stop work for 15 minutes on May 13--five months since the declaration of martial law. They also appealed for all traffic to halt for one minute at noon on the same day and cars and buses to sound their horns.

"Let's demand the freedom of our union activists and Lech Walesa . . . . The coordination of the protest in the entire country will be a test of our solidarity and our strength," the appeal said.

A second decree called on workers to organize committees for social assistance to members in difficulty, discussion clubs, and print shops for the publication of underground bulletins. Fulfillment of these tasks would help to coordinate nationwide protest actions and, if necessary, a general strike, the degree said.

Underground Solidarity leaders have said they will call a general strike if the union is formally outlawed. At present it has only been suspended. assistance to members in difficulty, discussion clubs, and print shops for the publication of underground bulletins. Fulfillment of these tasks would help to coordinate nationwide protest actions and, if necessary, a general strike, the degree said.

Underground Solidarity leaders have said they will call a general strike if the union is formally outlawed. At present it has only been suspended. assistance to members in difficulty, discussion clubs, and print shops for the publication of underground bulletins. Fulfillment of these tasks would help to coordinate nationwide protest actions and, if necessary, a general strike, the degree said.

Underground Solidarity leaders have said they will call a general strike if the union is formally outlawed. At present it has only been suspended.