At least 15 people died when a suicide bomber blew himself up at a Shiite mosque in Baghdad, the BBC reported.
The attack took place during night prayers and left a further 30 people injured, according to AP reports.
More than 2,500 Iraqis have been killed in sectarian violence since April this year, according to a United Nations report. May was the deadliest month in Iraq in 5 years, as more than 1000 were killed.
July has begun with a surge of violence, as bombs and gunmen murdered more than 100 people in the first two days of the month alone.
The violence engulfing the country comes as poltical tensions between the minority Sunni community and the Shiite majority boil over. Sunnis that feel marginalised by the Shiite-led government of Nouri al-Maliki have held mass demonstrations in recent months, calling for greater representation in government.
Deadly violence surges after the Iraqi security forces stormed an anti-government protest in Hawija in April, killing several protesters and wounding dozens more.