Ugandan President Yoweri Museveni has accused the United Nations of "preserving terrorism" in Democratic Republic of Congo.

In a statement from his office on Wednesday, President Museveni criticised the UN mission for failing to confront insurgents operating in mineral-rich eastern Congo where they launch deadly attacks.

"The UN operation in Congo and to some extent Somalia was conservation of terrorism. The terrorists are weak. They have had freedom of space but have made little progress in their ventures. If they were strong they would have made big impact," Mr Museveni told a team of UN investigators probing the December killing of 14 peacekeepers in eastern DRC.

The attack on the soldiers, mainly from Tanzania, by suspected Allied Democratic Forces (ADF), a Ugandan Islamist rebel group, was the worst against Monusco since its deployment in 1999.

Mr Museveni, a longtime critic of the UN's role in Uganda's western neighbour, said "it must be the people of the country to fight and defeat terrorism within their territory," but added that they can be assisted by "friendly forces".

Shortly after the ADF attack on UN peacekeepers, the Ugandan army launched an offensive – air and artillery strikes – against the insurgents.​