A suspected extremist attack at a church in eastern Congo killed at least 10 people and wounded more than three dozen, according to the country's army.

A group linked to Islamic extremists was suspected of being responsible for a bomb that went off in the Pentecostal church in the North Kivu province town of Kasindi, military spokesperson Anthony Mwalushayi told The Associated Press by phone.

A Kenyan national found at the scene was detained, Mwalushayi said. Congo's government urged people to avoid crowds and be vigilant as it conducted an investigation, said the minister of communication in a tweet.

Videos and photos of the attack seen by the AP showed dead bodies lying on the ground outside the church, including what appeared to be a dead child. The injured were being carried out of the church surrounded by other people screaming.

Violence has wracked eastern Congo for decades as more than 120 armed groups and self-defence militias fight for land and power. Nearly 6 million people are internally displaced, and hundreds of thousands are facing extreme food insecurity, according to the UN.

Fighters with the Allied Democratic Forces, a rebel organisation which is believed to have links to the the Islamic State group have carried out several attacks in Kasindi, which is located on the border with Uganda.

Troops from Uganda's army have deployed to eastern Congo to try to stem the violence, but the attacks have increased and spread. ADF attacks since April have killed at least 370 civilians and involved the abduction of several hundred more, a report by the United Nations last month said.

The rebel group has extended its area of operations to Goma and into neighbouring Ituri province.