At least four people were killed on Monday in Mozambique's Nangade district in the northern province of Cabo Delgado.

A report by independent Mediafax news site says assailants armed with machetes and firearms attacked the village of Changa at midnight.

An unnamed source told the Mediafax several houses were also burnt down.

The incident happened less than two days after security forces arrested three jihadists, and less than a week after security was beefed up in the region - which has been hit by violence blamed on Islamist militants.

Mediafax noted in its reporting that last week's attack in the Quissanga district was much further south, and given the distances involved, it is unlikely that the same group was responsible for both the Quissanga and the Nangade attacks.

It added that US oil and gas company Anadarko has started evacuating staff from the northern Palma district.

Anadarko is the operator for Area One of the Rovuma Basin, off the Cabo Delgado coast, where huge reserves of natural gas have been discovered.