Mozambique has asked the European Union for support in tackling a wave of militant attacks in the country's north by rebels with links to Islamic State, a conflict that has raised fears for stability and security in southern Africa.

The Islamist attacks in Cabo Delgado province date to 2017 but the violence has gathered pace this year, with insurgents seizing important towns for brief periods and hitting military and other key targets.

The Portuguese news agency Lusa said on Tuesday Mozambique had written to EU foreign policy chief Josep Borrell to ask for help in training its armed forces to battle the insurgency.

In the letter, Mozambique - which is a former Portuguese colony - also requested medical equipment and humanitarian assistance to help victims of the conflict, according to Lusa.

A EU spokesperson confirmed on Wednesday the bloc had received a letter from Mozambique's foreign ministry and said, without providing further details, a reply would be "prepared and sent in due time".

"The government of Mozambique and the EU have opened a policy dialogue, with a focus on humanitarian, development and security issues in Cabo Delgado," he said, adding the bloc was ready to discuss "options for assistance".

The EU will "review all available means of support in the light of the outcome of the dialogue", he said.

The plea for help came as a report from the World Food Programme on Tuesday said that over 300 000 people had fled the violence in Cabo Delgado to neighbouring provinces.

It also came amid accusations of human rights abuses by Mozambican authorities in the northern conflict zone.

Amnesty International reported earlier this month it had seen videos showing soldiers in government uniforms committing atrocities against alleged fighters in Cabo Delgado.

Mozambique's defence ministry dismissed the report, saying militants regularly impersonated soldiers.