Almost 90 people have been detained over the past 24 hours during a police operation launched in Russia's southern city of Volgograd in response to the deadly attacks on a railway station and a trolleybus in the city, operation spokesman Andrei Pilipchuk told the Rossiya 24 television station on Tuesday.

"Eighty-seven people were detained after they put up resistance to the police and did not have any documents allowing them to carry weapons. All of them were taken to police stations. An inquiry is currently being conducted in relation to them," he said.

A total of "1,500 small-sized buildings have been examined and more than 1,000 people have been searched," he said.

The Interior Ministry's operation under way in Volgograd is intended to help track down possible terrorists.

Thirty-three people were killed and dozens were injured in the December 29 blast at Volgograd's railway station and the December 30 attack on a trolleybus in the city.

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