Mosul , Iraq - A truck bomb targeting a police station in the northern Iraqi city of Mosul on Friday killed five US soldiers and two Iraqi soldiers, the US military said. Police said a man drove a truck through the security barrier surrounding the Iraqi National Police headquarters in southwest Mosul on Friday, then detonated explosives packed in the vehicle.

The blast also wounded 20 Iraqi security officers and one US soldier, the US military said in a statement.

A security push dubbed "Operation New Hope" has resulted in the arrest of more than 100 insurgents in Mosul, some 400 kilometres north of Baghdad, since it began in January.

But insurgents have responded with a near-daily string of deadly bomb attacks and assassinations in and around the capital of Nineveh province.

During a visit to Baghdad on Tuesday, US President Barack Obama reaffirmed the United States' commitment to withdraw its soldiers from Iraqi cities by July, saying the time had come for Iraqis "to take responsibility for their country."

But Iraqi Prime Minister Nuri al-Maliki last month said he might ask US troops to remain in the most dangerous cities of Iraq after the June 30 deadline.

"It is necessary for US forces to stay in Nineveh, since the greatest challenge Iraqi security forces face is in Mosul," Khasro Goran, deputy governor of Nineveh and the leader of the Kurdish Fraternal List, told the German news agency,(dpa)