Congo ? More than 1,500 Rwandan troops crossed the border into eastern Congo on Tuesday to join Congolese forces in an effort to oust Hutu rebels who participated in Rwanda’s genocide and have long been at the heart of the region’s conflict, officials said.

Congolese government spokesman Lambert Mende said the Rwandan forces arrived Tuesday morning and that the joint military operations would last 10 to 15 days.

“We have officially asked the Rwandan army to participate in the disarmament operations of the Interahamwe (Hutu militia) which have begun,” Mende said.

A Western diplomat, who spoke on condition of anonymity because of the sensitivity of the matter, said there was concern that Hutu militiamen might retaliate against civilians.

In a rare move, Congo and Rwanda have agreed to step up efforts against the Rwandan Hutu militants who have long destabilized the region. Still, neither country has been able to eradicate the Hutu rebels since they fled to Congo in 1994.