Iraq's Shiite prime minister declared Tuesday he will not be blackmailed into abandoning his bid for a second term, and the Kurdish president bowed to Shiite pressure to delay calling parliament into session until a deadlock is resolved over who should lead a unity government.

In Washington, U.S. Defense Secretary Donald H. Rumsfeld rejected suggestions Iraq is engulfed in a civil war but predicted there would be additional "bursts" of sectarian violence in the weeks ahead.

Rumsfeld also claimed that Iranian Revolutionary Guard elements had infiltrated Iraq to cause trouble.

"They are currently putting people into Iraq to do things that are harmful to the future of Iraq," he said. "And we know it. And it is something that they, I think, will look back on as having been an error in judgment."

He would not be more specific except to say the infiltrators were members of the Al Quds Division of Iran's Revolutionary Guards.

Rumsfeld asserted that media reports have exaggerated the violence in Iraq since an attack last month on a revered Shiite mosque touched off a wave of violent reprisals between sects.

"I do not believe they are in a civil war today," Rumsfeld said.

On Tuesday, scattered bombings, mortar blasts and gunfire killed 16 people.

The unrelenting violence has complicated already snarled negotiations to form a government reflecting Iraq's main ethnic and religious communities, which the United States and its allies hope will stabilize the country so they can start pulling out troops.

The senior British general in Baghdad, Lt. Gen. Nick Houghton, told The Daily Telegraph that most of Britain's 8,000 troops could be withdrawn by mid-2008. The Defense Ministry, however, described that as just one possible scenario and said everything depended on conditions on the ground.

Prime Minister Ibrahim Al-Jaafari suggested that the current standoff over his nomination had grown out of a personal dispute with President Jalal Talabani, who is at the center of a campaign by Kurdish, Sunni and some secular Shiite politicians to deny him a second term.

"No one can make bargains with me by enlarging personal disagreements," al-Jaafari told reporters at his office. "Dr. al-Jaafari will not be subdued by blackmail. Dr. al-Jaafari is not violating the constitution."

The Sunni Arab minority blames him for failing to control Shiite militiamen, who attacked Sunni mosques and clerics after the Feb. 22 bombing of a sacred Shiite shrine in Samarra. Kurds are angry because they believe al-Jaafari is holding up resolution of their claims to control the oil-rich city of Kirkuk.

In a bid to force a showdown in the dispute, Talabani said Monday he would order parliament into session March 12 for the first time since the December elections and the Feb. 12 ratification of the results in line with constitutional directives. Such a meeting would have started a 60-day countdown for lawmakers to elect a president, approve al-Jaafari's nomination as prime minister and sign off on his Cabinet.

Talabani was mistakenly counting on the signature of Vice President Adil Abdul-Mahdi, a Shiite who lost his own bid for the prime minister's nomination by one vote to al-Jaafari. Talabani had in hand a power of attorney from the other vice president, Ghazi al-Yawer, a Sunni, who was out of the country. The Shiite bloc closed ranks and Abdul-Mahdi declined to sign, for now.

A political committee representing the seven Shiite parties that make up the United Iraqi Alliance, the largest group in parliament, sent Talabani a letter Tuesday asking him to delay the first session until there is agreement on who should occupy top government positions, said Khaled al-Attiyah, an independent member of the alliance. Parliament speaker Hajim al-Hassani said a new date would be set Thursday.

"Talks are still under way between the main blocs in the coming parliament," he said. "We hope that during the coming days, we will be able to reach a basic level of agreement on when to call the Council of Representatives to convene."

Talabani planned to meet with Shiite leaders Tuesday night in a bid to resolve the crisis.

Shiite leaders are divided over a second term for al-Jaafari even though they came together Monday night to reject the move to drop him.

There were reports that Muqtada al-Sadr, the radical anti-American cleric whose backing insured al-Jaafari's nomination at the Shiite caucus last month, had threatened to order parliamentarians loyal to him to boycott the March 12 session if Abdul-Mahdi, the Shiite vice president, had signed the order to convene the legislature.

The Defense Ministry reported an increase in car bombings and mortar fire in the past week but said attacks appeared less effective. Maj. Gen. Abdul-Aziz Mohammed Jassim, head of the ministry's operations room, reported 552 attacks against U.S. and Iraqi security forces and civilians, of which 147 caused casualties.

In continuing violence Tuesday, a car bomb exploded near a restaurant on the fringe of Baghdad's Sadr City Shiite slum, killing three civilians and wounding three others.

Assailants attacked a Sunni mosque in west Baghdad with guns and grenades, killing a guard and torching two rooms. The gunmen ambushed police when they responded, wounding five officers.

Two bombs targeting U.S. patrols in two other neighborhoods killed at least one civilian bystander and injured five others, police said. There were no reports of American casualties.

Police said four Iraqi officers were killed in two separate attacks on police patrols in Baqouba and Beiji, north of Baghdad.

Two car bombs exploded almost simultaneously at separate sites in the mostly Shiite city of Hillah, south of Baghdad, wounding at least three people, police said.

At least three other people were reported killed in scattered shootings — a Sunni TV station official and an airport employee in Baghdad, and a police colonel in Beiji. Police found four more bullet-ridden bodies — two of them with their eyes gouged out.