According to new documents seized by Poland’s history institute, the country’s former president and Solidarity hero Lech Walesa was an informant for the Communist party’s secret police.
The documents were taken earlier this week from the home of a former communist-era interior minister, Gen. Czeslaw Kiszczak.
Lukasz Kaminski, head of the Institute of National Remembrance, said the documents appear authentic.
Lech Walesa has long denied being an informer in the 1970s.
He said the new materials could not originate from him, according to Polish radio.
The 279 pages of documents have not yet been properly analyzed, and will be made public in due course, Lukaszs Kaminski said.
Gen. Czeslaw Kiszczak’s widow had wanted to sell the documents, the institute said.
The state body has the power to prosecute.
Lech Walesa strenuously denied long-standing allegations of collaboration.
The former president was cleared of security service collaboration by a special court in 2000.
He was awarded the Nobel Peace Prize in 1983 for his role as leader of Solidarity – the first free trade union in the Soviet bloc.
Lech Walesa was elected Polish president in 1990, after the fall of communism.