At least 30 organised massacres of Jews in Poland during World War II were carried out by local people rather than occupying German Nazis, a new report has revealed.

It [report] brings to light information that was so far buried in the archives and puts the facts in a broad perspective

Pawel Machcewicz, editor of the report

The investigation by Poland's Institute for National Remembrance (IPN) was carried out after allegations made two years ago that Poles killed 1,600 Jews in the north-eastern village of Jedwabne in 1941.

The report - due to be published on Monday - says the Jedwabne pogrom was not an isolated incident, and that hundreds of Jews were murdered in similar attacks by Poles in more than 20 towns in the same region.

The evidence about the Jedwabne pogrom has shaken many Poles' view that they were only victims during the war, as all the massacres had previously been blamed on Nazi troops.

Buried information

The 1,500-page report "Around Jedwabne" lists the names of more than 100 murdered Jews and at least as many of suspected killers, according to Rzechzpospolita newspaper, which saw a preview of the report.

About three million Polish Jews died in the Holocaust

IPN researchers dug out records from 1946-1958 investigations and trials and translated written testimonies which survivors had given to a regional Jewish history commission.

"It brings to light information that was so far buried in the archives and puts the facts in a broad perspective," Pawel Machcewicz, editor of the report, told the Associated Press news agency.

But Mr Machcewicz said it was hard to establish figures for the exact number of Jews killed by Poles because of conflicting testimony and lack of other evidence.

Cover-up

For decades, Polish communist authorities covered up the role of Poles in the Jedwabne massacre, blaming Nazi killing squads for the murders.

But a book by Polish emigre historian Jan Gross "The Neighbours", published in 2000, challenged the official version of events.

Polish President Aleksander Kwasniewski made a historic apology for the killings at a 60th anniversary ceremony in Jedwabne last year, but insisted Germans were behind the pogrom.

After World War II, 12 people were convicted by a Polish communist court in 1949 for having helped the Germans carry out the killings.

They received sentences varying from 30 months to life in prison. One person was executed.