BAGHDAD - A department of the Iraqi prime minister's office is playing a leading role in the arrest and removal of senior Iraqi army and national police officers, some of whom have apparently worked too aggressively to combat violent Shiite militias, according to U.S. military officials.

Since March 1, at least 16 army and national police commanders have been fired, detained, or pressured to resign; at least nine of them are Sunnis, according to U.S. military documents shown to the Washington Post.

Although some of the officers appear to have been fired for legitimate reasons, such as poor performance or corruption, several were considered to be among the better Iraqi officers in the field. The dismissals have angered U.S. and Iraqi leaders who say the Shiite-led government is sabotaging the military to achieve sectarian goals.

"Their only crimes or offenses were they were successful against" the Mahdi Army, a powerful Shiite militia, said Brig. Gen. Dana Pittard, commanding general of the Iraq Assistance Group, which works with Iraqi security forces. "I'm tired of seeing good Iraqi officers having to look over their shoulders when they're trying to do the right thing."

The issue strikes at a central question about the fledgling government of Prime Minister Nouri al-Maliki: whether it can put sectarian differences aside to deliver justice fairly. During earlier security crackdowns in Baghdad, Maliki was criticized for failing to target Shiite militias, in particular the Mahdi Army, which is led by hard-line Shiite cleric Muqtada al-Sadr, one of Maliki's political supporters.

Before the most recent Baghdad security plan was launched in February, Maliki repeatedly declared he would target militants regardless of their sect.

Iraqi government officials denied that security force commanders have faced political pressure, and said Maliki was committed to targeting all criminals equally.

But some U.S. military officials say politics remains among the greatest hindrances to the development of the Iraqi security forces - a top priority for Americans in Iraq.

Col. Ehrich Rose, chief of the Military Transition Team with the Fourth Iraqi Army Division, who has spent several years working with foreign armies, said the Iraqi officer corps was riddled with divergent loyalties to different sects, tribes and political groups.

"The Iraqi army, as far as capability goes, I'd stack them up against just about any Latin American army I've dealt with," he said. "However, the politicization of their officer corps is the worst I've ever seen."

At the national level, some U.S. officials are increasingly concerned about the Office of the Commander in Chief, a behind-the-scenes department that works on military issues for the prime minister.

One adviser in the office, Basima Luay Hasun al-Jaidri, has enough influence to remove and intimidate senior commanders, and her work has stifled many officers who are afraid of angering her, a senior U.S. military official said. U.S. commanders are considering installing a U.S. liaison officer in the department to better understand its influence.

"Her office harasses [Iraqi commanders] if they are nationalistic and fair," the U.S. official said, speaking on condition of anonymity out of concern over publicly criticizing the Iraqi government. "They need to get rid of her and her little group."

Officials close to Maliki denied that Jaidri or her office were influencing or removing leaders in the security forces.

Jaidri could not be reached for comment yesterday.