Violence showed no signs of let-up Tuesday as a pair of suicide bombers killed seven people in Baghdad and insurgents kidnapped a governor in a western province demanding US pullout.

The first blast went off around 9:40 a.m. (0540 GMT) near a US- Iraqi joint patrol in central Baghdad, killing seven Iraqis and wounding 16 others, police said. Three US soldiers were reportedly wounded.

The explosion in the busy commercial Sadoun Street destroyed several civilian cars and smashed windows of surrounding buildings and shops.

A second car bomb hit a police headquarters on the bank of the Tigris River in southern Baghdad at midday, wounding a policeman.

"I saw a speedy vehicle dashing into the fence of the police headquarters and then a powerful explosion occurred, sending a plume of black smoke into the sky," said Salahudin Ibrahim, a witness sitting no more than 100 meters from the site.

Some of mortar rounds packed in the car did not explode and were scattered across the ground in the Jadriyah district, he said.

Meanwhile, the US military said Tuesday a marine died of wounds sustained in combat one day earlier west of Baghdad.

By Monday, 1,602 US soldiers have been killed in Iraq since the US-led invasion began in March 2003, according to a Pentagon tally.

Underlining the unabated turbulence, the governor of western Anbar Province was kidnapped when he was on his way from Ramadi to the border town of Qaim, a provincial council official said Tuesday.

"We knew this afternoon that Governor Raja Nawaf Farhan al- Mahalawi was kidnapped along with his four bodyguards," the official told Xinhua on condition of anonymity.

The kidnappers threatened to kill the hostages unless US forces withdraw from Qaim, a town close to the border with Syria.

US forces have launched a large-scale operation, dubbed Matador, in the province's vast desert area since Saturday to crack down on a new wave of insurgency after a new transitional government was sworn in last week.

Some 100 people have been killed in the operation, whereas only three US servicemen have been killed since the start of the operation.

The prominent Sunni Muslim Clerics Association denounced the operation as one compromising lives of innocent civilians.

US and Iraqi officials believe insurgents, some of them foreign fighters, are operating in the border area with support from abroad.

A number of cell leaders and coordinators linked to al-Qaida ally Abu Musab al-Zarqawi have been detained in this area.

In another development, one of leading militant groups, Ansar al-Sunna Army, said it was holding a Japanese hostage after it ambushed Sunday night a convoy carrying five foreigners protected by Iraqi guards.

The ambush took place near Hit, one restive town in Anbar, the group said in a statement posted on the internet.

Tokyo said Tuesday it would try to secure the release of the hostage, known as Akihiko Saito, 44, a security manager working with a security company.

Ansar al-Sunna made no demands, but said Saito was "severely injured" in the ambush. The statement could not be verified independently.

A young Japanese backpacker was abducted late last year and was later found beheaded in Baghdad after Tokyo refused to withdraw its troops from Iraq as the kidnappers demanded.

The al-Qaida allied group led by Zarqawi was behind the killing.

Japan has some 500 soldiers deployed in Samawa, 280 km south of Baghdad.