As reported by Ukraine's Security Service, seven suspected terrorists were arrested during raids in Kyiv and Ukraine's eastern city of Kharkiv on December 9.
The SBU security service said it had detained three Russian and four Ukrainian citizens after a shootout in which a special forces officer and the Ukrainian leader of the armed group were killed.
"Just in one place in the capital we found eight homemade explosive devices, four kilograms of TNT, automatic weapons, about forty hand grenades and 2,000 cartridges," spokeswoman Olena Gitlyanska said.
Kiev has repeatedly accused Moscow of backing pro-Russian separatists in eastern Ukraine both with weaponry and personnel, and of attempting to destabilize situation in other Ukrainian cities.
The detained Russians are believed to be members of Russian intelligence agencies, SBU official Oleksandr Tkachuk told a briefing. "Russian intelligence agencies are increasing their activities in peaceful Ukrainian cities," he said.