Investigators probing the deadly bombing at a Moscow airport are looking at up to 10 people from the Caucasus region as possible suspects.
Suspicions in the blast at Domodedovo Airport on Monday that killed 35 people and wounded 180 initially fell on Chechen rebels.
Prime Minister Vladimir Putin, perhaps sensitive about his failure to contain Chechnya's Islamist rebellion, has insisted there was no initial indication of a Chechen connection.
However, Chechen rebels have inspired Islamist insurgent activity elsewhere in the Caucasus and the state RIA Novosti agency said up to 10 people from there are being viewed as possible suspects.
The Kommersant newspaper reported that police are focusing on an insurgent group called the Nogai Brigade, which reportedly observes the strict Wahhabi form of Islam.
The group emerged in the Stavropol region and sided with Chechen separatist groups.
Kommersant, citing a source close to the bombing probe, said an ethnic Russian member of the group was of particular interest to investigators. The man is believed to be connected to a woman arrested in January for allegedly planning a suicide bombing in Moscow.
That arrest followed a New Year's Eve explosion on the outskirts of Moscow that killed one woman. The victim was believed to be preparing a bomb to attack a holiday gathering but it was inadvertently triggered early when the mobile phone provider sent a holiday greetings text message.
Authorities have said little about the airport bombing investigation. No consistent account of what happened has emerged, with reports variously saying it was a male or female suicide bomber, or a couple, or a bomb that was to be remotely detonated but exploded prematurely.
More high-ranking Russian transport officials have been fired in the wake of the bombing, including the head of air transport security for the western Russia region that includes Moscow.