A top Russian official says authorities have thwarted two separate attempted break-ins at Russian nuclear weapons installations.

Colonel General Igor Valynkin, who heads the department responsible for nuclear weapons safety, says lone perpetrators tried to illegally enter the facilities in the western part of the country in 2002 and 2003.

The official told journalists in Moscow Wednesday that the biggest potential threat to Russia's nuclear facilities is from Chechen terrorists.

He says Russia is using U.S. and German funding to boost security at nuclear facilities.

Some information for this report provided by AFP and AP.