Former Polish president and Nobel Peace laureate Lech Walesa.
Polish prosecutors on Tuesday said handwriting analysis proves that Solidarity freedom hero Lech Walesa collaborated with the communist-era secret police in the early 1970s.
The Institute of National Remembrance (IPN), which prosecutes crimes from the Nazi occupation and the communist era, said the former president and Nobel Peace laureate had signed a collaboration agreement and receipts for payment from the secret police.
There is "no longer any doubt" that the 73-year-old collaborated, IPN official Andrzej Pozorski told reporters.
Walesa, who co-founded the independent Solidarity union and then negotiated a bloodless end to communism in Poland in 1989, has been dogged by the allegations for years and has always denied them.
He did not react Tuesday as he was on his way to a Nobel gathering in Bogota, but his representative, lawyer Jan Widacki, told the Polsat News channel that "the case is not closed today" and said they may ask for a new handwriting analysis.
Pozorski said the authenticity of the secret police files, which include Walesa's alleged codename "Bolek", was determined by forensics experts in the southern city of Krakow.
The experts compared the files to other handwritten documents such as Walesa's applications for a passport, identity card and driving licence. Walesa had refused to submit samples of his handwriting.
The allegations against Walesa came resurfaced last year after the IPN seized previously unknown secret police files from the widow of a communist-era interior minister.
Walesa enigmatically admitted last year to having "made a mistake" and in the past said he signed "a paper" for the secret police during one of his many interrogations.
A book published by the IPN in 2008 alleged that while the regime registered Walesa as a secret agent in December 1970, he was cut loose in June 1976 due to his "unwillingness to cooperate".
On Tuesday, IPN head Jaroslaw Szarek said the institute "had no intention to erase Walesa from Polish history".
Poles have mixed feelings about Walesa. His boldness in standing up to the communist regime is still widely respected, but the combative and divisive tone of his later presidency earned him scorn in many quarters.