Police in Mozambique say they have seized 47 weapons from the headquarters of the main opposition party, and the home of its leader, Afonso Dhlakama.
The weapons, which included AK-47 rifles, were used in violent crimes in the capital, Maputo, police alleged.
Mr Dhlakama's Renamo party condemned the raids as an "invasion".
Renamo fighters and government forces have been involved in clashes since disputed elections in 2014, raising fears that a civil war could resume.
The 17-year conflict ended in 1992 with a peace deal which led to the former rebel group turning into an opposition party.
Mr Dhlakama was not at his Maputo home during the police raid, reports the BBC's Jose Tembe from the city.
He is based in the remote Gorongosa mountains in central Mozambique, which was his headquarters when he was a rebel leader.
Police commander Julio Jane said military uniforms and communication equipment had also been seized during the raids.
"At Mr Dhlakama's house, we found 38 AK-47 rifles and seven pistols," he said.
For its part, Renamo accused police of "stealing" about $4,000 (£2,800) from its properties during the operation.
Mr Dhlakama would respond "politically" to the raids, it added.
Renamo has carried out a spate of attacks on civilians and government targets since the disputed election, as it insists on the right to govern six of Mozambique's 10 provinces.