Chechens are voting in a Kremlin-backed constitutional referendum that promises wide autonomy for the breakaway republic within the Russian Federation. Chechen separatist rebels have already said they will only accept full independence, and earlier threatened to disrupt the poll.

Chechnya's Interior Minister, Ruslan Tsakyev, reports calm in the early hours of voting Sunday, with only a small portion of an estimated 540,000 eligible voters turning out.

The voters come from cities across Chechnya, as well as neighboring Ingushetia, where tens-of-thousands of Chechen refugees have been living in makeshift tent camps, until they feel secure enough to return home. Nearly 40-thousand Russian servicemen permanently stationed in Chechnya will also take part in the vote.

In order to be valid, the referendum needs to attract at least 50 percent of eligible voters.

Participants are being asked to approve a new constitution that would proclaim the breakaway region as an integral part of the Russian Federation, while also offering broad autonomy. The referendum will also ask voters to approve a series of laws related to eventual presidential and parliamentary elections in Chechnya. First results are expected on Monday.

Russian President Vladimir Putin has hailed the referendum as a path to peace for Chechen separatist rebels and Russian federal forces, who have been fighting on and off since the early 1990s.

Rebel Chechen President Aslan Maskhadov has rejected the vote, as a Russian attempt to perpetuate war. Mr. Maskhadov says only peace talks with the Kremlin can stop the bloodshed. But the Kremlin refuses to negotiate with him.

Critics of the referendum say a new constitution alone will not end nearly a decade of fighting between the rebels and Russian federal forces. And human rights groups are questioning the validity of a poll taken in conditions of war.

Russia controls much of the region, but is still losing troops almost daily in small-scale rebel attacks and skirmishes.

Security was stepped up in advance of the referendum, which was called shortly after the October siege carried out by armed Chechen rebels at a Moscow theater. More than 100 theater-goers died from the effects of knock-out gas, used by Russian special forces as they stormed the theater to free the hostages.