BAGHDAD  Bombs exploded near five Shiite mosques around Baghdad within 45 minutes on Friday as worshipers attended prayer services, killing at least 29 people in what appeared to be a coordinated attack against followers of the anti-American cleric Moktada al-Sadr.

The attacks, while less deadly than others in recent weeks, placed new scrutiny on the readiness of Iraqi security forces, a month after American troops pulled out of cities here. Some Sadrist leaders asked angrily why they were not protected, while others went so far as to accuse the government of actively making them targets now that American forces are less involved in daily operations. Leaders of a community of Iranian dissidents in Iraq, engaged in a bloody confrontation days ago with Iraqi soldiers, are making the same allegation.

“There is an organized campaign to liquidate Sadrists in which security forces are involved,” said Tariq al-Kenani, a Sadrist leader.

The Iraqi government quickly denied any involvement, and the United States Embassy here released a statement deploring the “barbaric attacks,” suggesting they were carried out by extremist groups.