Underground leaders of Poland's outlawed Solidarity trade union have called off protests planned for the first anniversary of the imposition of martial law next month and subordinated themselves to Lech Walesa.

In a statement given to Western correspondents today, Solidarity's underground leadership said Walesa's release from internment and the setting of a firm date next June for a return visit to Poland by Pope John Paul II had created "an entirely new political situation."

The statement added that the government's plans to end martial law next month have given rise to "hopes for at least a temporary truce between the authorities and society." In what appeared to be a significant change of tactics, the statement did not mention Solidarity's previous demand that it be allowed to resume activity as a labor union.

In the past two weeks, the authorities have dropped increasingly open hints that martial law will be lifted on Dec. 13, a year after its imposition. Emissaries have been sent to West European capitals to urge Western governments to respond by dropping economic sanctions against Poland.

What will replace martial law remains unclear. Polish government spokesmen have said that the end of martial law automatically will mean the release of the 1,000 or more Solidarity internees in "preventive" detention. But this still would leave several thousand persons who have been convicted of illegal trade union activity, plus a handful of dissidents charged with attempting to overthrow the state by force.

Some Polish political sources say the government probably will be given emergency powers during a transitional period, to enable it to keep some factories under military discipline. When Poland's legislature, the Sejm, meets on Dec. 13, it also may be asked to continue the present suspension of Poland's relatively liberal law on censorship, so the authorities can continue to maintain their tight control over news media.

In its statement, Solidarity's provisional coordinating commission made clear that future agreement will depend upon freeing "all political prisoners," reinstating workers fired from their jobs for political reasons, restoring the more liberal laws on censorship and independent associations and full self-management in industry.

"The lifting of martial law without the above guarantees would be another misleading gesture by the authorities, which would not fulfill the basic expectations of society," the statement said.

Significantly, it made no demand for restoration of Solidarity's status as an officially recognized labor organization. Dropping what had been a basic condition for national reconciliation was interpreted here as a major change of tactics by the union's underground leadership.

Part of the reason for this reappraisal is believed to be last month's poor response to Solidarity's call for an eight-hour strike to mark the second anniversary of the union's legal registration. Underground publications blamed the failure of the protest on threats of reprisals by the authorities and close supervision of factories by the Army and security police.

A Solidarity source said the union's new strategy is intended to strengthen Walesa's authority in any future negotiations with the government. By pledging to obey his decisions, the underground union leaders apparently seek to consolidate their movement around the man who led the Gdansk shipyard strike in August 1980 and became a symbol of hope for a more democratic society.

Apart from brief interviews immediately after his return home, Walesa has kept a low profile since his release from detention two weeks ago. He has said that he needs time to decide his next move, and he is believed to be waiting for the end of martial law.

Solidarity's provisional coordinating commission said that it still recognizes him as the union's "democratically elected chairman," despite the fact that Solidarity legally has been disbanded. The statement said that Walesa alone is empowered to set the conditions under which the underground leadership would dissolve itself.

The commission was set up last April to direct union activity while Walesa and other elected Solidarity officials were in custody. Since then, it has coordinated protests against martial law with varying results. Last week one of the commission's four original members, Wladyslaw Frasyniuk, was sentenced to six years in prison by a military court in the southwestern city of Wroclaw.

Solidarity's latest statement was signed by six underground leaders representing different chapters of the union: Zbigniew Bujak, Wladyslaw Hardek, Bogdan Lis, Janusz Palubicki, Eugeniusz Szumiejko and Jozef Pinior. The commission reportedly met on Nov. 22 to discuss the situation following Walesa's release and moves by the government to end martial law.

Last week the government-sponsored Patriotic Movement for National Salvation called for the earliest possible lifting of martial law and preparations for work on an amnesty. This was taken here as a signal for the start of a propaganda campaign aimed at convincing Poles of the government's commitment to economic and political reforms despite last month's dismantling of all existing trade unions, including Solidarity. Unions more susceptible to Communist Party control are being created in their place.