More than 500 armed militants in Chechnya and other parts of Russia's troubled North Caucasus surrendered to authorities as part of an amnesty that expired Monday, a Russian official said.

Authorities proposed the amnesty last summer as part of efforts to secure peace and normalcy in Chechnya. The offer, which expired at midnight, promised that surrendering militants would avoid prosecution unless they were suspected of grave crimes such as murder, rape or terrorism.

An official with the office of Dmitry Kozak, President Vladimir Putin's envoy to the southern federal district, told The Associated Press that more than 500 militants had turned themselves in; the official spoke on condition of anonymity since he was not authorized to speak to the media.

Among those surrendering during the weekend were two bodyguards and the driver of slain Chechen rebel leader Zelimkhan Yandarbiyev, officials said.

News agencies, meanwhile, cited Russia's national anti-terrorism committee as saying that 546 militants have surrendered since July.

The Kremlin has offered several similar amnesties in the past — with varying results. The latest proposal followed the July death of Chechen warlord Shamil Basayev, who masterminded the 2004 school hostage-taking in Beslan, Russia, and other major attacks during 12 years of nearly constant conflict in Chechnya.

According to rights groups, many of those who surrender join the ranks of Chechnya's security forces, which have been accused of involvement in abductions, torture and extrajudicial killings targeting civilians.

Large-scale battles in Chechnya ended years ago, but rebels continue to stage regular hit-and-run raids against federal forces and local allied paramilitaries. Militant attacks have also become increasingly common in other republics in the North Caucasus.