LAGOS - At least 20 Muslim worshippers were killed by unknown gunmen at a mosque in Nigeria's northern state of Kaduna, local police reported.

The police located the newly reported attack in the village of Dogo Dawa.

Nigeria's northern part has been plagued by violence in recent years, with frequent reports of shooting and bomb attacks, mostly claimed by the Boko Haram sect.

At least 815 persons have been killed in attacks by Boko Haram in Nigeria this year, the Human Rights Watch said in its latest report in October.

Hundreds of attacks by the sect have left more than 1,500 people dead since Boko Haram staged an uprising in the northern city of Maiduguri in 2009, according to the report.