Updated

BAGHDAD-- The top U.S. commander for Baghdad says Iraq's prolonged political crisis has encouraged a spike in violence and pushed frustrated citizens to begin holding back crucial tips on suspected insurgents.

The comments by U.S. Brig. Gen. Rob Baker reflect growing unease that Iraq's nearly seven-month impasse on forming a government could erode security gains. Baker also told reporters Wednesday that Iraq risks losing needed foreign investment.

Iraq's political leaders have been at odds over forming a new government since inconclusive elections in March.

Baker says Sunni insurgents have stepped up attacks to try to discredit Shiite-led authorities.

Shiite militias also have increased rocket strikes on Baghdad's protected Green Zone.