Mozambique's former rebel group Renamo says it has annulled a 1992 peace deal that ended a 16-year civil war after clashes with government forces.
A Defence Ministry spokesman said government forces had attacked a Renamo base in Sathundjira, near Gorongosa in central Mozambique, on Monday.
The operation comes after Renamo mounted attacks on police positions in the same area.
The fighting has damaged the decades old peace-deal between the Mozambique Liberation Front, also known as Frelimo, which has lead government since independence in 1975, and the Renamo movement, which is now an official opposition group.
A Renamo spokesman said the aim of the attack on its base was to kill its leader.
"Today, the Frelimo-government used troops and heavy artillery to attack the residence of the Renamo president, Afonso Dhlakama, to kill him in cold blood," Fernando Mazanga said.
"The taking of President Dhlakama's base by the special forces marks the end of multiparty democracy.
"This irresponsible attitude of the commander in chief of the country's security forces [President Armando Guebuza] signals the end of the Rome Peace accord."
Karl Sousa, a Mozambican journalist, told Al Jazeera that the whereabouts of Dhlakama were not known.
He said though the rebels lacked the capacity to engage government troops, they could resort to carrying out attacks against civilians.
Tensions between Renamo and the Frelimo-led government started escalating last year, after the group's leader Dhlakama set up camp in the Gorongosa mountains to retrain former guerrilla fighters.
The former rebels have been demanding the government renegotiate the terms of a 1992 peace accord.
Renamo became the official opposition after it signed a peace deal with the Frelimo-led government to end a 16-year civil war in 1992. But in April this year simmering tensions erupted in deadly clashes again.
The movement wants more representation on election bodies and in the armed forces.