Russian security services thwarted a terrorist bomb attack in Moscow on Thursday and detained a man preparing to detonate a bomb at a government building, the Federal Security Service (FSB) said.
The FSB described the man as a native of Central Asia and said he was working under instructions from an international terrorist group.
Such incidents are rare in the capital, but an FSB employee was killed in central Moscow in December when a man opened fire at FSB headquarters.
The FSB said it had found components for an improvised explosive device among the detainee's belongings, together with instructions for making explosives and correspondence with fellow militants.
"The offender planned to travel to a combat zone in the Middle East to participate in the activities of terrorist groups," the FSB said in a statement on its website.
It said investigations were being carried out and that a criminal case had been launched.