A suicide bomber blew himself up inside a Sunni mosque in central Iraq, killing at least 20 people in the middle of a sermon today.
The explosion took place in the town of Wajihiya in the ethnically and religiously diverse province of Diyala, which has seen an increasing number of attacks in recent weeks.
It was unclear who was behind the blast, the latest in a campaign of attacks that has raised fears of a return to full-blown sectarian conflict in a country where Kurds, Shi'ite and Sunni Muslims have yet to find a stable way of sharing power.
"I was in the first row of people praying. We were listening to the preacher give his sermon. Suddenly, a huge explosion shook the place," 22-year-old student Salman Ubaid told Reuters.
"I fainted and later found myself lying on the floor in Wajihiyia hospital with some shrapnel in the head," he added.
Sectarian tensions have been inflamed by the civil war in neighbouring Syria, which has drawn in Shi'ite and Sunni fighters from Iraq and beyond to fight on opposite sides of the conflict.
Sunni insurgents, including the al Qaeda-affiliated Islamic State of Iraq, have been recruiting from Iraq's Sunni minority, which resents Shi'ite domination since the US-led invasion that toppled Saddam Hussein in 2003.
They have regained strength in recent months and strike on a regular basis.
More than 460 people have been killed in militant attacks in July so far, according to violence monitoring group Iraq Body Count.
That is still well below the height of sectarian bloodletting of 2006-07, when the number of people killed in militant attacks sometimes exceeded 3000 in one month.
At that time, sectarian violence took longer to wind down in Diyala than almost any other province in Iraq. The province is often described as a microcosm of the country, with Shi'ite Muslims, Sunnis, Kurds and Arabs living close together.
"The situation in Diyala is very dangerous," said lawmaker Mohammed Othman, who is from the province.
Asked who he thought was behind the violence, Othman said it could be Shi'ite militias or members Sunni al-Qaeda, attacking members of their own sect to provoke a reaction. "The goal is to widen the gap between people and return Iraq to civil conflict," he added.
Separately, a suicide bomber tried to enter a Shi'ite mosque in Jbeila, north of Hilla, 100 km (60 miles) south of Baghdad. He failed and blew himself up, killing a policeman who had blocked his way.
Another policeman was killed in an almost identical incident yesterday in the town of Iskandariya, also north of Hilla, police said.