Maputo - Twelve people have been killed in a suspected Islamist attack in northern Mozambique, with thousands of villagers fleeing the area into neighbouring Tanzania, police sources said Sunday.

Early Friday, "there was an attack in Nangade district, where there are no security patrols. The attackers killed 12 people, mostly women and children," a police source in Cabo Delgado province, who asked not to be named, told AFP.

The attack took place in the village of Chicuaia Velha, just a few kilometres (miles) from Tanzania, forcing several thousand people to cross the border to seek safety, police said.

A local journalist said the villagers were killed by machete or died when their houses were set on fire by the attackers.

It was the third such incident in the last month in Cabo Delgado, leaving 20 dead in all.