More than 100 tanks have been seized from a militia group loyal to former Libyan leader Colonel Muammar Gaddafi.
Nearly 30 rocket launchers were also captured when security forces raided a camp in Tarhuna, near Tripoli on Wednesday.
In all, 13 people were arrested during the operation, but three escaped. The seizures were announced on Thursday.
Government officials say the Brigade of the Faithful group was behind twin car bombings in Tripoli last Sunday morning which killed two people.