WARSAW, Poland (AP) — Polish Prime Minister Donald Tusk said Tuesday that three people were recently arrested on suspicion of links to foreign-sponsored sabotage, adding to nine others already under arrest.

Tusk was speaking at a weekly news conference about what steps his government was taking to protect Poland against hostile activity, including incidents with suspected links to Russian intelligence services.

“Another three people were arrested” on Monday night, Tusk said, as he praised the efficiency of Poland’s national security services. That brings the number of those under arrest to 12.

On Monday, Tusk said that nine people have been jailed on allegations of having “engaged themselves directly into acts of sabotage in Poland, on commission from Russian (intelligence) services” and described them as “hired people, sometimes from the criminal world, and nationals of Ukraine, Belarus and Poland.”