At least 16 people were knifed to death weeks after being taken hostage in the Democratic Republic of Congo's east, in bloodletting blamed on armed Islamists, military and local sources said Tuesday.

According to local civilian sources, the victims, who included two women, had been held by members of the Allied Democratic Forces (ADF), which the US says is linked to the Islamic State group.

The hostages were killed along a main highway near Idohu, in the restive Ituri province, according to local official Dieudonne Malangai.

Ituri's military governor Johnny Luboya Nkashama speaking in Komanda, some 40 kilometres (25 miles) from the slaughter, condemned the killings.

-We will reinforce our presence in the region- he told a meeting with local residents.

-Helicopters are already on the scene and other military personnel are on their way with trucks and munitions to assure security in the region and to organise safe convoys along this road- the governor added.

He promised to return in a month to reevaluate the situation in the area, where thousands have fled their homes to avoid the violence.

-The objective is to clean up the area completely and allow the population to return to the villages- Nkashama told a sceptical crowd at a public meeting.

-It was hoped that the state of siege would restore security but people continue to die every day- he added.

The vast central African country's government placed Ituri and the neighbouring North Kivu province under a state of siege in May, in a move aimed at stepping up the fight against armed groups.

The ADF is the deadliest of scores of militias operating in the region.

It began as an armed Ugandan Muslim group, and has been active in mineral-rich eastern Democratic Republic of Congo for 30 years.

The DRC's Catholic Church says the ADF has killed around 6,000 civilians since 2013, while a respected US-based monitor, the Kivu Security Tracker (KST), blames it for more than 1,200 deaths in the Beni area alone since 2017.