Bishops Back Walesa in Presidential Runoff : Poland: The nation’s Catholic church throws its support to Solidarity’s leader in Sunday’s voting.

Solidarity leader Lech Walesa, facing a runoff this weekend against dark-horse candidate Stanislaw Tyminski in the race for the national presidency, has received the backing of Poland’s powerful Roman Catholic church.

A pastoral letter issued by Polish bishops was read at most church services Sunday, and although the letter itself did not name Walesa, it noted that the “leadership of our state should be entrusted to a person who, guided by Christian values, will guarantee continuation and consolidation” of the struggle against “the yoke of totalitarian constraint.”

Most pastors, if samplings in Warsaw are a fair indication, were far more direct in their commentaries delivered along with the reading of the letter.

“Practically,” said one pastor, “we have one candidate to vote for. The other is simply a KGB agent, as we could plainly see from television and other publications, who has been placed in Poland in order to destroy Poland’s newborn democracy and throw us back into the darkness of a totalitarian system.”

At the same time, Prime Minister Tadeusz Mazowiecki, knocked out of the running for president by Tyminski in the Nov. 25 elections, asked his supporters to vote for Walesa in the final round of the election, which is scheduled for Sunday.

“In the face of the irresponsibility that may endanger Poland and everything we have been struggling toward for 10 years, we should cast our ballots for Mr. Walesa,” Mazowiecki said in a weekend speech launching the Union of Polish Democracy, a group that, he added, may be devoted to opposing Walesa in the future.

Mazowiecki was a key adviser to Walesa for nine years, dating from the earliest days of the Solidarity movement, but the presidential campaign brought about a sharp cleavage between the two men and their followers.

In the face of the challenge by Tyminski, an unknown Canadian businessman, most of Mazowiecki’s followers, although bitterly antagonistic to Walesa’s ambitions during recent months, have urged voters to support Walesa.

The 42-year-old Tyminski has been bedeviled in the last week by mounting accusations in the Polish press that his campaign staff is composed of a large number of former Polish SB (security service) agents of the former Communist regime.

In a speech Sunday, Tyminski did little to dampen the suspicions over his background, asserting that he had been approached “repeatedly” to work as a spy for the Communist authorities. He said he rejected the offers.

“I had proposals several years ago to work for the SB, . . . and I refused,” Tyminski said in a rally in Bialystok in eastern Poland. Those approaches came, he said, after he had emigrated from Poland.

He said that he had also been approached before he left Poland, 21 years ago, to go to Sweden, but “I did not agree to collaborate.”

The pro-government daily newspaper Gazeta Wyborcza alleged Monday that Tyminski was able to get a passport to leave Poland for Sweden in 1969, when he was a student, only after talking to military intelligence officers. The newspaper did not cite a source for its information.

Also on Monday, United Press International reported that it has documentary evidence showing that Tyminski had been judged unfit for regular military service in 1968, a year before he emigrated to Canada to make his fortune.

A two-page document from the local military draft commission that handled Tyminski’s case said he qualified for military service in 1967, but a 1968 entry in the document said he was unfit for basic military service and could only serve in the auxiliary, such as in hospitals.

According to UPI, the document cited paragraphs 66 and 71 of the military commission qualifying code. Paragraph 66 refers to “epilepsy with frequent bouts and changes in the area of intellect and behavior.” The explanation for Paragraph 71 is listed as “reactive psychosis,” a mental disease characterized among other things by an inability to differentiate critically.

A third entry in 1969 judged him again unfit for basic military duty but eligible for auxiliary duty, on grounds of Paragraph 69--”an incorrect psychic personality which is treatable.”

Tyminski, who returned to Poland last September, has denied all the charges.

Last week, Poland’s interior minister said the ministry’s records show that Tyminski received seven visas for travel to Poland from the Polish Embassy in Tripoli, Libya, between 1980 and 1989. Tyminski has denied repeatedly that he has ever been in Libya.