Prime Minister Nuri al-Maliki's spokesman said the deadly attack may be linked to the bloody civil war in neighbouring Syria, where jihadists have battled Kurdish forces.

Later on Sunday, a suicide bomber attacked mourners at a Shiite mosque south of Baghdad, killing 24 people, the latest in a string of sectarian attacks on mosques and funerals.

A statement from the Kurdish asayesh security service said a suicide bomber detonated explosives at the entrance to their headquarters in Arbil, the capital of the northern region.

Asayesh forces then clashed with four more bombers, killing them, after which another detonated an explosives-rigged ambulance.

Kurdistan region health minister Raykot Hama Rashid told journalists that six asayesh members were killed and more than 60 people wounded in the attack.

An AFP journalist heard blasts in Arbil, and heavy gunfire. Smoke was seen rising into the air, and ambulances raced to the scene.

"We were inside the building when there was a huge explosion outside, and when we tried to go out to see what happened it was crowded, and there was shouting everywhere," said Farhan Samed Kamil, an asayesh member who lost two fingers in the attack.

"After a while there was a second explosion. That's all I remember," he told AFP at a hospital in Arbil.

"When we entered the headquarters to evacuate the wounded, a second huge explosion happened, and three ambulances were seriously damaged," said Ismail Abdullah, an ambulance driver who was also hospitalised.

While other areas of Iraq are plagued by near-daily violence that kills hundreds of people each month, the three-province Kurdistan region has largely been spared.

Sunday's blasts were the first to hit Arbil since May 2007, when a truck bomb exploded near the same asayesh headquarters, killing 14 people and wounding more than 80.

"Syria has affected all of us," Maliki's spokesman Ali Mussawi told AFP, adding that the Arbil attack may be "one of the offshoots of the Syrian crisis".

Iraqi security analyst Ali al-Haidari agreed.

"The attack is linked to the differences between the Kurds and Al-Nusra Front," Haidari said of a rebel jihadist group operating in Syria.

"Today's attack is Al-Nusra Front's revenge against the Kurds inside Kurdistan," he said.

Iraq's autonomous Kurdish region has become increasingly embroiled in the bloody conflict raging across the border.

Clashes last month between Kurdish forces and jihadists seeking to secure a land corridor connecting them to Iraq pushed tens of thousands of Syrian Kurds across the border, seeking refuge in Iraqi Kurdistan.

Regional president Massud Barzani has threatened to intervene in the Syrian conflict to protect Kurdish civilians, although officials have since backtracked on his remarks.

Sunday's blasts came a day after results were announced for the region's parliamentary elections, which saw an opposition movement place second ahead of Iraqi President Jalal Talabani's party.

Iraqi Kurdistan enjoys a high level of autonomy from Baghdad, and the regional parliament has passed laws on a wide range of issues. The Kurdish region also operates its own security forces and visa regime.

Attacks elsewhere in Iraq killed 38 more people on Sunday, officials said.

In the deadliest incident, a suicide bomber targeted mourners at Al-Hussein Mosque south of Baghdad, killing 24 people and wounding 27.

Militants have carried out a series of recent attacks targeting mosques and funerals in central Iraq, raising the spectre of a return to the all-out Sunni-Shiite conflict that peaked in 2006-2007 and killed tens of thousands of people.

Five soldiers were killed in Kirkuk province and three Sahwa anti-Al-Qaeda fighters in Diyala province.

Attacks in Baghdad province killed a further five, among them a primary school teacher shot dead at a school, and gunmen killed a local official in the northern city of Mosul.

The latest violence brings the death toll to more than 790 people in September and upwards of 4,600 this year, according to AFP figures based on security and medical sources.