The United Nations says there's been sharp increase in attacks in Afghanistan targeting places of worship, religious leaders and worshippers, including attacks against Shiite Muslims.

The U.N. Assistance Mission in Afghanistan has documented 51 incidents of such attacks since January 2016, resulting in 850 civilian casualties: 273 killed and 577 wounded.

UNAMA's report was released on Tuesday.

The report says the figure is nearly double the number of such attacks documented between 2009 and 2015, when there were about 475 such attacks.

The report noted that in October, a suicide attacker lobbed a grenade into the women's section of the Imam-e-Zaman Shiite mosque in the Afghan capital, Kabul, and detonated his suicide vest amid the worshippers, killing 57 and wounding 55.

The Islamic State group claimed responsibility for the attack.