Iraq's Prime Minister Nuri al-Maliki said Saturday that the withdrawal of U.S. combat forces from Iraqi cities at the end of June showed Iraq can handle its own security, despite a wave of bombings this week.

The U.S. pullback from Iraq's urban centers scheduled to be finished at the end of the month has been seen as a milestone on Iraq's road to sovereignty after years of military occupation.

But a spate of bombings in the capital and in northern Iraq this week, including two of the bloodiest attacks in more than a year, have shaken the confidence of Iraqis in their own forces.

We are on the threshold of a new phase that will bolster Iraq's sovereignty, Maliki said. It is a message to the world that we are now able to safeguard our security and administer our internal affairs.

Two big bombings in Baghdad and the northern Iraqi city of Kirkuk this week killed more than 150 people between them. On Friday, a bomb killed at least 13 people at a market in Baghdad. A spattering of other bombs has also fueled apprehension.

U.S. and Iraqi officials have warned they expect the number of attacks to rise as the U.S. troops pull back, and also in the run-up to parliamentary elections next January.

We have high trust in our security forces to administer security and pursue al-Qaeda remnants and criminal gangs, Maliki said.

He added that Iraq had achieved comparatively good levels of security, not just through better policing but efforts at political reconciliation between Iraq's divided factions -- something his critics often accuse him of dragging his feet on.

If they (militants) want to bring down the political process, we say, it won't collapse, unless national unity is shaken, Maliki said.