Bombs exploded across Iraq on Wednesday, killing at least 16 people, police and medical sources said.
It was not immediately clear who was behind the attacks, but Sunni Islamist militants including al Qaeda, have been regaining ground in Iraq, seeking to undermine the Shi'ite-led government.
Prime Minister Nuri al-Maliki flew to the United States this week seeking military supplies to counter insurgents who have pushed the civilian death toll above 3,000 so far this year.
In the latest violence, a suicide bomber blew himself up in a group of people who had gathered to assess the damage from two earlier blasts in the town of Tuz Khurmato, 170 km (100 miles) north of Baghdad, killing four people, police and medics said.
A car bomb went off inside a parking lot west of Baquba, killing five people, and another blast near a gathering of young people in the street killed a further three, police said.
In the town of Muqdadiya, 80 km (50 miles) northeast of Baghdad, another car bomb went off in an open door market, killing four people, police and medics said.
The surge in violence has reversed a decline in sectarian bloodshed that peaked in 2006-2007.
Officials in Baghdad say the bloodshed is a spillover from the civil war in neighbouring Syria, which has drawn hardline Sunni Islamists into battle against forces loyal to President Bashar al-Assad, whose Alawite sect derives from Shi'ite Islam.
Al Qaeda's Iraqi and Syrian affiliates merged this year to form the Islamic State in Iraq and the Levant, which has claimed responsibility for attacks on both sides of the border.
Insurgents have exploited growing discontent among Iraq's Sunni minority, which complains of marginalisation under the Shi'ite-led government that came to power following the U.S.-led invasion that overthrew dictator Saddam Hussein in 2003.