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

Hashemi, a Sunni, ignored an arrest warrant to stage a news conference in Iraq's semiautonomous northern Kurdish territory to proclaim his innocence.

He said he was willing to go on trial to clear his name, but preferably in Kurdistan and not Baghdad, where his house and office were raided and his bodyguards stripped of weapons.

"I categorically deny plotting attacks on other politicians," he said. He said Prime Minister Nouri al-Maliki, a Shiite, was "100 percent responsible" for the allegations.

On Monday, state-run television showed "confessions" by three of Hashemi's bodyguards, who said the vice president had paid them to run hit squads against military personnel and police over the last two years.

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 was not clear what, if anything, the administration was prepared to do. About the time Carney spoke, President Obama and Vice President 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.

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

However, U.S. officials are aware of at least one attempt by Iraqi security forces to coerce confessions that implicated Hashemi, 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, Ahmed Mohammed Sami, who said he had been tortured while held by the Iraqi army in Diyala province.

"In total he counted seven times that he lost consciousness during episodes of torture in which he was told to agree to statements implicating Vice President Tariq al-Hashemi . . . in terrorist activities," the cable reports.