By Robert Walker
BBC correspondent in Kigali
Rwanda's army says it has repulsed an attack by Hutu rebels from neighbouring Democratic Republic of Congo.
Remnants of Hutu militias crossed into DR Congo after the genocide
A military official said at least 16 rebels were killed attempting to attack a Tutsi village inside Rwanda's border.
Rwanda is currently commemorating the 10th anniversary of the genocide in which some 800,000 people, mainly Tutsis, were killed by Hutu militias.
Remnants of the militias regrouped after the genocide in Congo, from where they continue to operate.
Details about the rebel attack, which occurred late on Thursday night, are only now emerging.
The head of Rwanda's armed forces, Major General James Kabarebe, told the BBC a force of some 250 Hutu rebels crossed into north-west Rwanda with the aim of killing Tutsis.
But he said they were intercepted by the Rwandan army, and at least 16 rebels were killed.
General Kabarebe said the insurgents then fled back into DR Congo, carrying a number of wounded with them.
The attack appears timed to coincide with commemorations marking the 10th anniversary of the genocide, and it is seen as an indication of the rebels' intention to fight on.
Last year their military leader surrendered and returned to Rwanda, raising hopes that others would follow.
But instead, a more hardline leadership has now taken command.
The Rwandan government estimates there are still up to 20,000 rebels.
They include members of the extremist Hutu militias who fled to Congo after participating in the genocide.
Previous attempts by the rebels to infiltrate Rwanda were crushed by the Rwandan army, but human rights groups reported widespread army abuses against civilians in the process.