Warsaw, Feb 2 (DPA) At least 500 agents of the feared East German Stasi secret police operated in Poland under communism, infiltrating the anti-communist Solidarity trade union, Polish Radio reported quoting a German official.

Hanna Labrenz-Wiess of Germany's Gauck Institute charged with archiving Stasi files, told Polish Radio Friday, the Stasi began operations in Poland in 1978 after the election of Polish Cardinal Karol Wojtyla as Pope John Paul II.

Stasi agents operated independent of Poland's Security Service (SB) and were most focussed on infiltrating and sabotaging the work of the anti-communist trade union Solidarity.

Under the leadership of Lech Walesa, Solidarity, as the first and only free trade union in the communist bloc, secured a bloodless negotiated end to communism in Poland in 1989.

Nearly 20 years after the demise of communism, Poland is still coming to terms with the dark issue of who did and who did not work as secret agent and informant for the secret police.

A string of revelations that Roman Catholic clergy had been recruited as secret police informants has recently rocked the staunchly Catholic homeland of the late Pope John Paul II.

As a vocal anti-communist, he himself was also especially targeted by communist secret police. It is believed Soviet secret services may have orchestrated the 1981 attempted assassination which saw Turkish gunman Mehmet Ali Agca shoot the pontiff in broad daylight in St. Peter's Square amid thousands of visiting Catholic pilgrims.