MOSCOW -- Russia's security service says it has arrested 10 people who were preparing terrorist attacks in Moscow and St. Petersburg and who had contacts with the Islamic State group.

The statement from the Federal Security Service was reported by Russian news agencies on Saturday.

The security service, known by its acronym FSB, said those arrested were from Central Asian countries; it did not specify the countries but said the arrests were made in co-operation with the former Soviet republics of Kyrgyzstan and Tajikistan.

The FSB said homemade bombs and firearms were seized in the Saturday arrests and the suspects admitted to having contact with Islamic State figures.