The government of Rwanda is warning of an imminent attack against Rwandan Hutu rebels who have moved into eastern Congo. UN representatives are calling it an ominous development.

"Rwanda must respect international law and the authority of the Security Council, which is still present in the region," the council said in a statement.

Rwanda has invaded Congo twice since 1996 in search of Rwandan Hutu rebels, many of whom were involved in the 1994 Rwandan genocide.

The 1998 invasion sparked a war that drew in the armies of a half dozen African nation, leaving more than three million people dead.

The UN has announced it will send more peacekeepers into Congo's northern province in response to the threat.