Russian FSB
© RIA Novosti
The Russian Federal Security Service (FSB) confirmed on Thursday the detention of dozens of Ukrainian citizens suspected of planning terrorist attacks in seven Russian regions. The detainees admitted officers of the Security Service of Ukraine (SBU) instructed them to make a photo survey of Russian military maneuvers in regions bordering Ukraine, FSB said.

Russia's NTV television earlier reported that 25 Ukrainians, including three activists of the radical Right Sector movement had been detained in Russia on suspicion of planning terrorist attacks in the Rostov, Vogograd, Tver, Orel, Belgorod regions and republics of Kalmykia and Tatarstan.

'As a result of measures taken on the basis of information about the preparation of terrorist acts on the territory of the Russian Federation by activists of the so-called Right Sector movement during the period from March 14 to March 16, some 25 Ukrainian citizens have been detained,' the FSB said.

The detainees admitted officers of the Security Service of Ukraine (SBU) instructed them to make a photo survey of Russian military maneuvers in regions bordering Ukraine, FSB said.

In addition, they were to establish contacts with Russian radicals.

They were detained 'before committing any illegal actions damaging Russian security,' the Russian service said. Ukraine's SBU dismissed the information as 'nonsense,' Ukraine's UNIAN news agency reported.

The Russian Foreign Ministry called on Ukrainian authorities Wednesday to take decisive action in disarming radical paramilitary groups, while expressing concern about continued extremist activity in the country.

The Right Sector, an ultranationalist Ukrainian paramilitary group, faces an outright ban in Ukraine following a siege of the country's parliament building last week.

The movement is known for its leading role in the violent protests that brought the incumbent Ukrainian leadership to power in late February.

Its activists used clubs, petrol bombs, and firearms in street fighting against Ukrainian police.

One of its most notorious members, Olexander Muzychko, was wanted by Russia on suspicion of torturing and murdering at least 20 Russian servicemen in Chechnya in the early 2000s.

He was killed by Ukrainian special forces last month.