Ten people were injured Tuesday evening in a grenade blast in central Rwanda, a police spokesman said, adding that it was not yet clear whether the blast was an attack.

"We have not confirmed whether this was a blast or an attack," the spokesman Theos Badege told AFP, adding that no one was killed in the explosion.

The blast happened in the early evening, he said, in the Muhanga district in the centre of the country. The device was in a road on the edge of a bus park where vendors were selling phone cards.

Most of the recent grenade attacks in Rwanda have been carried out in the capital Kigali, but in July last year a grenade blast wounded 21 people at a market in the southwest of the country.

Earlier this month a similar blast in the capital Kigali killed two and wounded 16.

Security forces have in the past blamed attacks on the Democratic Forces for the Liberation of Rwanda (FDLR), a Rwandan Hutu rebel group based in the neighbouring Democratic Republic of Congo, as well as former security officials in exile.

Several people are awaiting trial accused of carrying out grenade attacks in Kigali and provincial towns in 2010.

In March last year a grenade attack in Kigali injured seven people. Two people were killed in a previous attack in January of that year and seven were injured, two fatally, in a blast after presidential elections in August 2010.

The most frequent targets are bus stops and markets during the evening rush hour.

Accidental blasts also occur from time to time in Rwanda, usually when children stumble across unexploded devices.