A Polish underground leader said in an interview made available today that although the underground has been fortified in recent months, he expected a long struggle that could take years to restore labor rights. He added that he expected no concrete results from the much anticipated visit to Poland this month of Pope John Paul II.

Zbigniew Bujak, the former Solidarity chairman in Warsaw and perhaps the best known of the former union leaders in hiding since the imposition of martial law 17 months ago, said the May Day demonstrations were evidence of a stronger underground. The protests, which drew tens of thousands in 20 Polish cities in the face of massive police intimidation, reflected improved cooperation between regional underground groups.

He said the underground leadership's general strike call for Nov. 10, which failed, marked "a crucial point for the union" in that it forced a change of strategy in the direction of less demonstrative activities and a greater focus on the gradual establishment of underground units.

He urged people seeking to found independent unions to think in terms of "years, not weeks or months."

The remarks, Bujak's first interview in six months, were printed in an edition of the weekly underground paper Tygodnik Mazowsze dated May 26. Despite his skepticism about the immediate effects of the Polish-born pope's pilgrimage, he said it would contribute to a strengthening of society's resistance against Communist authorities. His statements could help dampen expectations among many Poles who, embittered over the abolition of the Solidarity trade union last year, are hoping the papal trip will bring new advantages quickly.

Other former Solidarity activists have voiced concern in private conversations that contrary to the joyous papal visit in 1979, which let loose a sense of nationalism and self-expression that later flowered into the Solidarity movement, this year's pilgrimage could lead to disappointment and an erosion of faith in the pope and the Roman Catholic Church if high expectations go unfulfilled.

"I think anyone who expects tangible results from the visit will probably get nothing out of it," said Bujak. "It can bring nothing concrete and one should not even expect this. Simply speaking, in such a situation Communist authorities as a principle make no concessions."

The government of Gen. Wojciech Jaruzelski, while resisting a personal papal appeal to lift martial law and grant a blanket amnesty to political prisoners before the visit, is hoping John Paul will deliver soothing homilies during his week-long stay that will help pacify the country. But Bujak said he was not afraid that Poles would feel less ready to demonstrate after the pilgrimage.

"The visit will intensify pacifistic tendencies but this does not mean weakness in our situation," said the 28-year-old ex-union boss. "To the contrary, it means our strength."

Predicting huge crowds at the events along the pontiff's tour, Bujak, as if taunting the police to be on the look-out for him, added: "I too will welcome him on the route."

Bujak is a member of the five-man provisional coordinating committee for Solidarity, the primary group responsible for formulating underground strategy. The committee has called for calm during the week-long papal visit, which begins June 16.

Bujak said he would consider giving up underground activities only if authorities allowed union pluralism, under which workers could choose the type of labor movement they want.

Although the new trade union law has a provision ending the current one-union-per-factory rule in 1985, the Communist Party's Politburo yesterday again ruled out the concept of pluralism, arguing this was a kind of Trojan horse notion for opponents of socialism to try to secure a permanent place in Poland's political system.

Praising Lech Walesa, the leader of the former Solidarity union who also has been urging the authorities to allow a more competitive union movement, Bujak said: "Lech has completely different possibilities than the underground and is making splendid use of them."

But in contrast to Walesa's repeated expressions of willingness to enter new talks with Jaruzelski's government, Bujak rejected the suggestion of bargaining, saying the government was disintegrating amid internal power struggles.

"The authorities as they now exist are not partners for us," he stated. "The party apparatus is doing its thing, the security apparatus its thing, the military, administrative and economic apparatus their own things. Nobody is listening to anyone else."