Alexander Bortnikov said relatives of a woman who was killed while allegedly preparing a New Year's Eve suicide bombing in Moscow are suspected of providing assistance in the airport bombing. It was not immediately clear if any of them were among those detained, but Bortnikov said some suspects are still being sought.
The Jan. 24 bombing in the international arrivals terminal at Domodedovo Airport killed 36 people and wounded 180.
Investigators last week said the bomber was a 20-year-old man from the Caucasus region in Russia's south, which is gripped by an Islamic insurgency that appears to be intensifying. The bomber's name has not been released and officials have provided only vague details of the investigation.
However, an autopsy showed "a huge amount of highly potent narcotic and psychotropic substances in parts of the suicide bomber's body," Bortnikov, the Federal Security Service head, said in a televised meeting with President Dmitry Medvedev.
Russia's main investigative body, the Investigative Committee, last week claimed the bombing had been solved, but Medvedev sharply criticized that assessment as premature.
"Neither the prosecution nor the Investigative Committee or other officials have the right to announce that a crime has been solved" until a perpetrator has been convicted and sentenced, Medvedev said.
The president, often criticized as ineffectual in comparison with his powerful prime minister Vladimir Putin, has repeatedly made strong statements about the bombing in an apparent attempt to assert he is in control.
The dressing-down given to Bortnikov and Investigative Committee head Alexander Bastrykin could also be seen as an oblique criticism of Putin. The prime minister, asked by reporters on Wednesday about the bombing investigation, said "It can be said that, as a whole, the matter has been solved," according to Russian news agencies.
Bortnikov did not give details on how many people who had information about the bombing had been detained or whether they were detained in connection with the blast. He also did not say if they revealed information while being held for other crimes.
He also did not give details on the alleged relatives of the Dec. 31 bomber.
In that blast, a woman was killed on the outskirts of Moscow, reportedly by a bomb that was to have been deployed in the city's central Manezh Square where Muscovites throng for holiday celebrations.
Some media reports have cited sources as saying the bomb was to have been set off by a cellular phone and that it exploded inadvertently when the phone received a holiday greetings text message from the cell phone operator.
Violence attributed to Islamic separatists and to criminal gangs breaks out in Russia's Caucasus almost daily. In Dagestan, where the bloodshed is most frequent, a small bomb exploded in the capital, Makhachkala, on Thursday morning, killing a city official involved in razing illegal structures, said Interior Ministry spokesman Vyacheslav Gasanov.
In another Caucasus republic, Kabardino-Balkariya, a traffic policeman died Thursday after being shot the night before while he and a partner were checking a motorist's documents, the republic's Interior Ministry said.
David Nowak in Moscow contributed to this report.