WARSAW, Poland - Communist authorities fabricated documents that suggested Lech Walesa was a communist collaborator to try to stop the Solidarity founder from being awarded the Nobel Peace Prize, Polish investigators say.

Evidence gathered as part of an ongoing investigation shows that communist secret security forged documents in the 1980s that suggested Walesa was their agent, said Zbigniew Kulikowski, a prosecutor at the state National Remembrance Institute.

The documents, in which Walesa's handwriting and signatures were forged, were sent to the Norwegian Embassy in Warsaw and to the Nobel Prize committee, he said Wednesday.

Allegations have been made over the years that Walesa was a collaborator, but most Poles consider the claims untrue and have long believed the documents were forged. Walesa said late Wednesday that the counterfeit documents were very well done and had misled some people, but that he was glad the truth triumphed.

In 2000, a special screening court cleared Walesa of collaboration allegations.

Walesa was awarded the Nobel Prize in 1983 in recognition of his pro-democracy struggle. His wife Danuta and son Bogdan traveled to Oslo to receive it, because Walesa feared the communists would not allow him back into Poland if he left.

In 1989, Walesa led the Solidarity anti-communist movement in negotiations with the authorities that eventually ended communism in Poland. He served as Poland's president from 1990-95.