Armed and masked police raided the opposition New Times magazine on Thursday, pressing journalists to hand over interview recordings used in reports on alleged abuse of authority by the OMON riot police.

A handful of police entered the magazine's Moscow office seeking recordings of interviews and other material used in a February report that cited police sources as saying OMON officers are permitted to commit abuses when breaking up protests.

"We suggest you voluntarily — voluntarily — give us the recordings of the interview with the current and former OMON staff," the officer in charge of the raid told New Times editor Yevgenia Albats in the presence of a Reuters reporter.

The raid was part of a defamation investigation by law enforcement authorities into current and former officers whom the magazine interviewed for its report, Albats said.

"If you refuse to do this, we will put this in writing," the officer, Colonel Stanislav Pashkovsky, said before lighting up a cigarette in the magazine's office, which was decorated with a large poster critical of the government.

Albats, a vocal Kremlin critic, refused to hand over the recordings, citing legislation protecting journalists' sources.

"One of the sources gave his name, and the second source … gave us an interview on terms of confidentiality and repeated several times he did not want to give his name because it would put his life in danger," she said in an interview.

Albats later said she did hand over a 43-page interview transcript but refused to divulge the names of any confidential sources or provide any material, such as audio or video recordings, that could help police identify any source.

She said the law prohibits media from disclosing confidential sources unless there is a court order and the case in question has come to trial.

The case initiated in connection with the magazine's report is still being investigated and has not come to trial.

Police searched the magazine's premises in April, an action condemned by media rights group Reporters Without Borders, which said it was illegal under the circumstances.