Zimbabwe is among a host of southern African countries readying for military intervention to stop a deadly insurgency by Islamists in northern Mozambique, a top official said on Monday.

President Emmerson Mnangagwa's spokesperson, George Charamba, said the Southern African Development Community (Sadc) was edging closer to sending troops to the troubled country.

Mr Charamba spoke as five Sadc leaders began a day-long summit in Maputo to tackle the conflict in the Cabo Delgado region.

"Sadc is fast moving towards a subregional response against Islamic insurgency, an initiative which started when President Emmerson Mnangagwa was chairman of the Sadc Organ on Defence, Politics and Security," he said.

The Defence ministry said Zimbabwe will contribute troops and equipment to a Sadc brigade once the leaders sanctioned the intervention.

"Intervention in that conflict will be done within the framework of the Sadc brigade," the Ministry said in response to reports claiming that plans by Zimbabwe's military to deploy troops in Mozambique were at an advanced stage.

"The Sadc brigade was launched in August 2008 and is made up of military, police and civilian members from Sadc member countries...Zimbabwe as a member state contributed troops and equipment to the brigade that will be deployed to such missions."

Speculation has been rife that Zimbabwe's special forces are already operating in Mozambique to secure infrastructure such as railway lines.

Landlocked Zimbabwe relies on Mozambican ports to transport its imports and export goods to overseas markets.

The country also relies on a pipeline from Beira for its fuel imports and, in the 1990s, was forced to deploy troops during the Mozambican civil war to secure the infrastructure.

Authorities, however, say this time around any military intervention would be led by Sadc.

"Zimbabwe is a member state of Sadc and as such any decisions to assist another member state in conflict resolution will always be guided by relevant treaties and conventions," the Defence Ministry said.

On Monday, the United Nations High Commission for Refugees (UNCHR) said at least 400,000 people have fled militant attacks in Cabo Delgado.

UNHCR warned that the conflict could spill over into neighbouring countries if left unchecked.