Moscow: Russian investigators said on Saturday that they had solved this week's Moscow airport bombing and were on hunt for the masterminds of the horrific attack.

But they provided no details about their findings amid speculation that the suicide bombing was staged by a group of Islamists from the country's troubled North Caucasus region.

"The act of terrorism at Domodedovo has been solved," Russian news agencies quoted Investigative Committee spokesman Vladimir Markin as saying in a three-sentence dispatch.

Monday's attack on the country's busiest airport shook Russia's confidence just as it was gearing up to present a modern new face to a flood of foreign visitors who are expected here for the 2014 Winter Olympics and 2018 World Cup.

The blast at the international arrivals hall killed 35 people and prompted President Dmitry Medvedev to sack several transport security officials.

He also signed a raft of new security measures Saturday that focused on supplying the country's vast transport system with new screening and other security equipment.

The pace with which investigators reported solving the case underscores the seriousness of the dilemma it posed to Medvedev.

The Kremlin chief has trumpeted a modernisation message that aims to convince foreign investors that Russia was cleaning up its image and becoming more Westernised.

But the blast forced Medvedev to rewrite part of his keynote address at the Davos World Economic Forum and admit before the world community that Russia was still unable to eradicate terror.

Most of Medvedev's wrath has thus far been directed against Moscow airport's management and a series of mid-ranking officials who are responsible for individual security measures.

The country's powerful Federal Security Service (FSB) - which was once led by Prime Minister Vladimir Putin - has thus far avoided all criticism for allowing the second attack to strike Moscow in less than a year.

Unofficial reports said the FSB had been on the lookout for three suspects in the days preceding the blast. No one has been arrested or claimed responsibility for the bombing.

The dearth of official details about the investigation has been somewhat compensated by a flood of unofficial - and often contradictory - reports about who may have staged the attack and why.

A security source told Interfax on Saturday that the police were already hunting for a handful of prime suspects.

"Several people are suspected of organising and carrying out the terror attack on Domodedovo," the unnamed security official said.

"We are working on their arrest," the source added.

Most Russian news reports have zeroed in on an ethnic Russian member of a North Caucasus militant group who vanished last year.

Police sources said the man - Vitaly Razdobudko from the Stavropol region just north of the Caucasus mountains - was probably not the suicide bomber but the organiser of the attack.

His police mug shot has since graced the pages of Russia's biggest dailies and his unusual biography has been detailed in full.

But there has been no official evidence linking Razdobudko to the bombing and it was not clear if investigators had him in mind when reporting the case solved.

Footage of the explosion has been captured by a closed-circuit camera and replayed on Russian television. But speculation continues to swirl over what actually set off the blast.

The Kommersant business daily reported on Saturday that the suicide bomber was wearing a plastic explosives belt that was also filled with nuts and bolts.

One source suggested that the explosive belt may have been set off remotely or by mobile phone. But another newspaper said the bomb appeared to be timed.

Earlier accounts said the explosive went off in a bag that may have been placed on the floor.