Iranian authorities have carried out summary executions, arbitrary arrests and torture on a troubling scale despite the cease-fire in the war with Iraq, a new report from the United Nations says.

The study for the U.N. Human Rights Commission said a wave of executions in 1988, especially after an invasion by anti-government forces based in Iraq, halted a two-year decrease in the number of executions. It said the scale of recent abuse in Iran "justifies international concern."The 42-page report, released Friday, lists 1,096 names of people alleged to have been executed between late July and mid-December. "But it was alleged that there were in all probability several thousand victims," said the report.

The U.N.-mediated cease-fire in the eight-year war took effect Aug. 20.

"Arrests are apparently so numerous that some high officials have requested the authorities to act with more moderation," said the report. It said detention of relatives of people accused of political crimes "appears to be a common practice."

The study also pointed to continuing reports of ill-treatment and torture of prisoners. "Investigation, trial and serving of sentence are reportedly effected under duress, hardships and different kinds of torture," it said.

The report, which was done from outside Iran, collected information from witnesses and reports in Iranian and foreign media.