A car bomb has exploded in a central Baghdad square killing at least five people and wounding seven, an interior ministry official said.

A bomber set off hidden explosives inside a public bus in in Al Tayaran square in the Bab-al-Sharji area at about 11.40am (0740 GMT) on Friday, police Major Mohamed Younis said.

The blast occurred as the minibus was parked at a bustling bus station in the square.

Younis said the bomber detonated a belt of explosives strapped to his body beneath his clothes, but eyewitnesses said they saw the man leave the bus minutes before it exploded.

Shopkeeper Nadhem Hassan said he saw a man "enter the bus and leave it very quickly", adding that he saw six burnt bodies in the vehicle.

"A man left a bag in a minibus shortly after he had boarded. It exploded just after he left," a police officer said. "Five people were killed and seven others wounded."

Other incidents

A US patrol came under a grenade attack in the al-Adhamiya district early on Friday, killing an Iraqi civilian, Iraqi journalist Walid Khalid told Aljazeera.

US forces suffered no casualties or material damage , he added.

Unidentified fighters also assassinated Ali Abd al-Rida Khalaf, an Iraqi Oil Ministry employee, in al-Shurta tunnel west of Baghdad, he said.

Ali Abd al-Rida Khalaf was also a member of the Shiite al-Dawa party, led by the Iraqi Prime Minister, he added.  

Fighters also assassinated former Iraqi army Brigadier Abbas Sultan Salam in front of his house in al-Sidiya neighbourhood in Baghdad, he said.

US soldiers killed

Meanwhile, a US soldier was killed and another wounded by a roadside bomb on a road linking the cities of Falluja and Ramadi, about 70km west of the Iraqi capital, the military said in a statement.

The explosion occurred while the soldiers were taking part in a combat logistics patrol on the road.

Also on Thursday, an Army soldier assigned to the 2^nd US Marine Division was killed by small arms fire during an operation in Ramadi, the military said.

Turkmen officials Killed

Three officials in the Turkmen Front were killed and one wounded on Thursday by an unidentified armed group in Mosul, 390km north of Baghdad. An official in the group said they were attacked while leaving their office.

One policeman was also killed in the northern city on Thursday,, a police source said.

Six bodies of people who were shot dead were found on Thursday and Friday in different areas of Mosul, a medical source said.

PHOTO CAPTION

A British soldier looks through his rifle scope while on patrol in the southern Iraq city of Basra September 23, 2005. (REUTERS)