KIRKUK, Iraq - A triple bombing killed 27 people - most of them police officers - and wounded scores Thursday, heightening tensions in the ethnically divided northern city of Kirkuk that is already on edge after a string of kidnappings and attacks on security officers.

The new violence adds to the strains that beset Kirkuk, which has long been plagued by ethnic squabbles over land and oil fields.

Iraqi and U.S. officials long have feared that the dispute over Kirkuk and oil-rich lands surrounding it - sandwiched between Arab villages and an autonomous Kurdish region - could destabilize Iraq if American forces leave at the end of this year on schedule.

"This shows there is no government in this country," railed Ahmed Salih, 55, sitting next to a hospital bed where his 30-year-old son, Omar Ahmed, lay with bandages around his head and legs.

The first blast, a bomb stuck to a car in a parking lot in central Kirkuk, lured policemen out of their fortified headquarters to investigate about 9 a.m., Police Capt. Abdul Salam Zangana said. Three minutes later, a car packed with explosives blew up within the crowd of police.

"The boots of police officers were scattered at the scene," said one officer, Ahmed Hamid, who survived.

The third bomb, planted on a road leading to a hospital, set cars and trucks ablaze when it exploded about 550 yards away less than an hour later. Zangana said it targeted a police patrol near a mosque.

In all, the blasts killed 27 and wounded at least 60, provincial health director Siddiq Omar said. Eyewitness Adnan Karim described the scene as "a chaos of terror and fear."

Kirkuk, 180 miles north of Baghdad, has been a flash point for years. Its Kurds, Arabs, and Turkmen each claim the city as their own.

Kirkuk's two largest ethnic groups have their own competing security forces - the Arab national police and the predominantly Kurdish peshmerga.

Within the last 10 days, police patrols in Kirkuk have been targeted in five roadside bombings and an army base has been hit by two Katyusha rockets, Police Col. Sherzad Mofari said.

In Mosul, another major city within the disputed territories, four Iraqi army soldiers were killed by a roadside bomb Thursday afternoon, a policeman said.

Also, kidnappers killed a policeman and a Christian construction worker in Kirkuk. The latter's body was dismembered after his attackers gave up on collecting the $100,000 ransom they had demanded.

American military commanders have long worried that the simmering fight over Kirkuk could provoke violence that engulfs the rest of the country. For several years U.S. troops have worked to build partnerships between Iraqi army forces and the peshmerga to secure the swath of disputed lands that stretches over three northern provinces - and over some of the world's most lucrative oil reserves.

But as U.S. troops withdraw, there is little indication the Kurdish-Arab partnership will hold.