Slovakia's spy agency says Russian agents have significantly increased their activities in Slovakia and all other NATO and European Union countries in connection with the crisis in Ukraine.

The agency, known as SIS, made the comments in its annual report but didn't provide any details.

Relations between Russia and the West have sunk to post-Cold War lows after Moscow's 2014 annexation of Ukraine's Crimean Peninsula and its support for a pro-Russian insurgency in eastern Ukraine.

The SIS says Russia has been actively supporting the separatists in Ukraine to keep the country under its sphere of influence. It says Ukraine's conflict strengthened the position of conservatives close to Russian President Vladimir Putin.

The agency says foreign spies have tried to infiltrate Slovak state offices, security forces and influence the public opinion.