BAGHDAD — Iraqi Vice President Tariq al Hashimi struck back at the Shiite Muslim-led government Tuesday, dismissing official allegations that he had masterminded multiple assassinations of security officials as based on fabricated evidence.

In what amounted to the second round of a trial-by-television, Hashimi, a Sunni, ignored the arrest warrant over his head to stage a press conference in Iraq's semiautonomous northern Kurdish territory to proclaim his innocence.

Hashimi said he was willing to go on trial to clear his name, but preferably in Kurdistan and not the Iraqi capital, where his house and office have been raided and his bodyguards stripped of their weapons and their badges granting access to the Green Zone.

"I categorically deny plotting attacks on other politicians," he said. "I am within the law. I am not with the terrorists. I am not with violence." He said Prime Minister Nouri al Maliki, a Shiite, was "100 percent responsible" for the allegations.

In round one Monday night, state-run Iraqiya television broadcast "confessions" by three of Hashimi's bodyguards, who said the vice president had paid them to run hit squads against military personnel and police over the past two years.

The spectacle raised doubts whether a fair trial could be held anywhere. An even bigger question was whether the increasingly sectarian dispute would cause permanent damage to Iraq's fragile democracy just days after the United States withdrew its last military forces.

In Washington, White House spokesman Jay Carney reiterated that the Obama administration was "obviously concerned" about the developments and had been in contact with Iraqi leaders of "all parties."

But even as some Iraqi politicians described the United States as perhaps the only outside nation able to mediate the dispute, it wasn't clear what, if anything, the administration was prepared to do. About the time Carney spoke, President Barack Obama and Vice President Joe Biden were at Andrews Air Force Base, Md., for a ceremony marking the end of the war and the return home of the military colors of U.S. forces in Iraq.

"We urge the Iraqi authorities charged with this responsibility to conduct their investigations into alleged terrorist activities in accordance with international legal norms and full respect for Iraqi law," Carney said.

The Iraqiya bloc, led by secular Shiite politician Ayad Allawi, which shares power with Maliki's State of Law bloc, has already said it will boycott the parliament and on Tuesday said it was withdrawing from the cabinet, where it has about 10 ministerial posts.

Hashimi, who appeared on the verge of losing his composure several times, repeatedly described himself as a moderate who believed in punishing anyone involved in terrorism. In a somewhat odd remark, however, he issued an apology to the families of victims of what until now has been a string of unexplained killings.

What puzzled many observers was why Maliki had ordered the public airing of confessions, rather than collect the evidence needed to convict Hashimi. A number of lawmakers from different parties, including critics of Maliki, say they believe the allegations are factual.

However, U.S. officials were aware of at least one previous attempt by Iraqi security forces to coerce confessions that implicated Hashimi, a longtime Maliki critic. A November 2006 diplomatic cable obtained by WikiLeaks reported a meeting between U.S. officials in Iraq and a former Iraqi prisoner named Ahmed Mohammed Sami, who said he'd been tortured with electric shocks and other methods while in Iraqi army custody in Diyala province.