Two people have been killed in a grenade explosion in Rwanda's capital, Kigali, police have said.

Sixteen others were wounded by the blast near a market in Gasabo district.

The security forces have blamed previous grenade attacks on the FDLR Hutu Rwandan rebels in neighboring Democratic Republic of Congo.

Leaders of a new opposition party in exile, who were also accused of having links to grenade blasts in 2010, condemned Tuesday night's explosion.

"Either the government is implicated in these periodic grenade attacks, so as to find pretext to crack down on the political opposition at a time of dwindling internal and foreign support, or the regime has lost the ability to protect its citizens," Theogene Rudasingwa, of the opposition Rwanda National Congress (RNC), said in a statement.

Mr Rudasingwa, was once a close adviser to President Paul Kagame and is ex-secretary general of the Rwandan Patriotic Front, the rebel outfit that toppled the Juvenile Habayarimana government. Rudasingwa is now based in the US and was tried in absentia last year, along with three other former top RPF aides who accuse Mr Kagame of being intolerant to dissent, and found guilty of threatening state security and propagating ethnic divisions.

More than 20 other people are awaiting trial accused of being behind several other blasts since 2010, mainly in Kigali.

Following the other attacks, the government said the RNC was waging an organized campaign to destabilize the country.

Some 800,000 Tutsi and Hutus were killed in the 1994 war.

President Kagame, who has promised not to run for president beyond the two terms constitutionally, stipulated term limit has been praised for keeping the country relatively peaceful, and on an economic rise that is not marched by any of Rwanda's neighbors in the region.