Attacks in Iraq killed 17 people on Wednesday, including 14 who died in twin bombings in the northern town of Tal Afar, just weeks before the country is due to host a landmark Arab summit.

The violence, which also left 24 people wounded, comes two days after suspected Al-Qaeda gunmen killed 27 policemen in a pre-dawn rampage in western Iraq, as officials insisted Baghdad was ready for the March 29 meeting, which UN Secretary General Ban Ki-moon is set to attend.

"At 1:00 pm (1000 GMT), a car bomb exploded in west Tal Afar, and five minutes later, a suicide bomber blew himself up among the people who rushed to the scene," said town mayor Abid al-Al Abbas.

"In total, 14 people were killed and 15 wounded."

Athil al-Nujaifi, governor of Nineveh province of which Tal Afar is part, earlier put the toll at 13 dead and 15 wounded in a car bomb and suicide attack. Differing tolls are common in the chaotic aftermath of attacks in Iraq.

Tal Afar, a majority Shiite Turkmen town 380 kilometres (240 miles) north of Baghdad in mostly Sunni Nineveh, was the site of twin car bombings on December 14 in a market and restaurant area that killed two people and wounded 27.

The attack in Tal Afar comes two days after suspected Al-Qaeda militants stormed the town of Haditha in western Iraq, in a pre-dawn shooting spree that killed 27 policemen.

In March 2006, then US president George W. Bush Tal Afar hailed Tal Afar as a model town due to the low levels of violence at the time.

In Baghdad on Wednesday, two separate attacks in which insurgents placed bombs inside vehicles -- one a taxi and the other a bus -- killed three people and wounded nine, an interior ministry official said.

The capital's security command centre released a statement calling on residents to "check their vehicles before driving and, after driving, do not leave your car in an unguarded public space."

Violence in Iraq has declined in recent years after peaking in 2006 and 2007. According to official figures, 150 people were killed in February.

The latest attacks come ahead of a March 29 summit of the Arab League in Baghdad, the first non-emergency meeting of the 22-nation body to be held in the Iraqi capital in more than 30 years.

President Jalal Talabani said on Monday that preparations for the summit were complete, "and Baghdad is now ready to receive the Arab leaders."

UN chief Ban Ki-moon is due to attend the summit, the first since the Arab Spring uprisings swept away veteran strongmen in Tunisia, Egypt, Libya and Yemen, Iraqi deputy foreign minister Labid Abbawi told AFP on Wednesday.