Investigators say the suicide bomber who killed 35 people and wounded 180 at Moscow's Domodedovo Airport was a 20-year-old man from the volatile southern Caucasus region.

The federal Investigative Committee made the announcement in a website statement on Saturday.

It is the first official indication since Monday's blast at the international arrivals hall that authorities have made progress in their probe of the attack, and appears to support popular suspicion that Islamist rebels from the south could be behind the bombing.

Chechen rebels have claimed responsibility for a number of deadly attacks over the years, including ones against the Moscow metro and at the same airport.