At least seven people have been killed in unrest in eastern Democratic Republic of Congo's North Kivu province, local officials said on Saturday, after people took to the streets to protest against a surge in deadly attacks by suspected Islamist rebels.

The Allied Democratic Forces (ADF), a rebel group affiliated to the Islamic State, are alleged to have killed more than 40 people in an attack on Mayikengo village this week and over 80 in attacks on other villages in the province the previous week.

The insecurity has fuelled public frustration, leading to the killing of two soldiers and their driver in Lubero territory by a crowd who torched their vehicle overnight on Friday, local official Julio Mabanga told Reuters.

On Saturday, further clashes in the area between security forces and local residents led to the deaths of another three people: a civilian, a soldier, and an agent of the ANR national intelligence service, Mabanga said.

A similar protest broke out in the city of Butembo on Saturday, with hundreds of youths taking to the streets wielding sticks, chanting and singing songs to denounce the widespread insecurity, according to a Reuters reporter.

"I'm here at this roundabout, barricading the road. We sympathise with our killed compatriots," said Daniel Sivanzire Paluku, one of the protesters, who said they needed to block the roads to monitor who was coming and going.

Butembo Mayor Mowa Baeki Telly confirmed one civilian was killed during clashes between security forces and protesters in the city.

The ADF originates in neighbouring Uganda, but is now based in mineral-rich eastern Congo. It has pledged allegiance to Islamic State and mounts frequent attacks, further destabilising a region where many militant groups compete for influence and resources.

It has not been possible to reach the ADF for comment on the attacks.

The U.S.-based SITE Intelligence Group, which follows militant websites, said on Friday Islamic State had published communiques from its so-called Central Africa Province division claiming responsibility for the killing of 51 people in attacks in North Kivu this week. It has also claimed to have beheaded over 60 people in a single attack in the province on June 7.