Suspected Islamist militants who have wreaked havoc in northern Mozambique for more than two years went on a rampage attacking several villages over a 24-hour period, police and local authorities said Tuesday.

The latest series of attacks were staged between Monday afternoon through Tuesday morning and left hospitals, schools, a bank and construction equipment destroyed and ransacked.

Police sources told AFP that militants on Monday attacked two villages in the districts of Muidumbe and Quissanga, located some 150 kilometres (90 miles) apart.

In Muidumbe they "set fire to shipyards, trucks and bulldozers" belonging to a bridge construction firm, said one police source.

Before the raid, the attackers used loudhailers to warn villagers "not to run away but stay inside the house," the source said.

On Tuesday morning, the insurgents staged another attack in Muidumbe district.

"They destroyed the hospital and looted medical drugs. They also attacked the local (bank) and blew up an ATM and looted bank notes which they distributed themselves," said a local police officer. 

"Then they raised their flag at the local hospital," said the source.

On Monday night the militants set houses on fire in the Bilibilza village, about 60 kilometres from the provincial capital Pemba.

A shadowy jihadist group has killed more than 900 people in northern Mozambique since 2017, according to the Armed Conflict Location & Event Data Project (ACLED).

The unrest has forced hundreds of thousands of locals to flee and raised concern among energy giants operating in the gas-rich region.

The identity of the assailants remains unclear.

Locals in the predominantly Muslim province call the group Al-Shabaab, but it is not linked to the group of the same name operating in Somalia.

In Muidumbe, the militants recorded a video of themselves addressing locals in the region's local vernacular of Kimwani and Swahili.

"We are Muslims like you. We don't want to hurt you. If you do not report us to the police, we will live well with you," said one militant in the video, wielding a Kalashnikov.

"But if you denounce us, tell these pigs (police) where we are hiding, the next time we come here we will kill everything, even chickens and eggs, old people and babies," the militant said, flanked by his fellow militants.

Provincial police spokesman Augusto Guta refused to comment on the attacks.