Russian security services had received warnings that an attack was planned at a Moscow airport, reports say after a blast killed at least 35 people at the city's largest air hub Domodedovo.
"The special services had received information that an act of terror would be carried out at one of the Moscow airports," a security source told the RIA Novosti news agency.
"Agents were seeking three suspects but they managed to access the territory of the airport, witness the explosion which their accomplice carried out and then leave the airport," the source said.
The suspects most likely brought the suicide bomber to the airport in a car that they parked in the long-term car park, the source said.
"A tip-off with a warning that something was being prepared appeared one week before the explosion," an airport security source told the Lifenews.ru website. "Even the place, by the customs, was named."
The source complained that the airport had cut numbers of security staff by half in recent months, and alleged corruption within the airport police, saying they spent their time soliciting bribes from migrants.
"All the police did was fleece people flying in from Central Asia," the source claimed.
The blast took place in the international arrivals hall where passengers are met, just after the customs control.
An airport spokeswoman confirmed it was a free access zone that does not require a boarding pass or a special badge to enter.
The bombing could have been a second attempt, after a woman died in Moscow last year while apparently preparing an explosive device, a law enforcement source told the Interfax news agency.
A woman died December 31 in an explosion at a sports club in southeastern Moscow and her husband, who took part in rebel movements in the North Caucasus, was arrested, the source said.
"The circumstances of the explosion give us reason to believe that the woman was being trained to carry out a terrorist attack," the source said.
