A coordinated attack involving a suicide bomber at an open-air election campaign meeting in central Iraq killed 25 people on Saturday.

A coordinated attack involving a suicide bomber at an open-air election campaign meeting in central Iraq killed 25 people on Saturday, the latest in a spike in unrest two weeks before provincial polls.

Supporters of the candidate Muthanna Ahmad Abdulwahid had been gathered at around lunchtime in the restive city of Baquba, 60 kilometers (35 miles) north of Baghdad, when a militant threw a grenade, before a suicide bomber blew himself up, a police colonel and a medic at Baquba hospital said.

At least 25 people were killed and 60 others were wounded, the officials added, though Abdulwahid appeared to have been unharmed.

Iraq has been plagued by attacks against election candidates ahead of provincial council polls due on April 20, with 12 hopefuls killed already, according to an AFP tally.

Diplomats have also raised concerns over a government decision to postpone elections in two provinces which, combined with the fact that four were never slated to vote, means that just 12 of Iraq's 18 provinces will cast ballots.

The polls will be the latest in Iraq since a March 2010 parliamentary election and the first since the withdrawal of US forces at the end of 2011.

Also on Saturday, a civilian was killed and two anti-Qaeda militiamen were wounded in a bomb blast northwest of Baghdad, and security forces found the body of a policeman who had been kidnapped near the capital a day earlier.

Violence has spiked markedly ahead of the provincial elections, with 271 people killed in March, the highest such figure since August.