Iraq issued an arrest warrant for its Sunni vice president on anti-terror charges Monday, deepening a crisis that one leader warned threatened the unity government, just a day after US troops left.

Less than a year before the cabinet was formed, Iraq's fragile political truce appeared to be unraveling, with the Sunni-backed Iraqiya bloc boycotting parliament and Prime Minister Nuri al-Maliki calling for the sacking of one his deputies, a Sunni who branded his government a "dictatorship".

"According to article four of the anti-terrorism law, an arrest warrant has been issued against Vice President Tareq al-Hashemi and it is signed by five judges," Major General Kamal Hussein, a senior interior ministry official, told a news conference.

The judicial committee that issued the warrant earlier barred Hashemi from leaving the country. On Sunday evening, he was briefly escorted off a plane at Baghdad airport bound for the Kurdish region.

News of the warrant came with the vice president still in Kurdistan and as state broadcaster Al-Iraqiya TV aired footage showing what the interior ministry said were Hashemi's bodyguards confessing to planning and carrying out terror attacks, and receiving funding and support from Hashemi.

At least 13 of Hashemi's bodyguards have been detained in recent weeks, though it was unclear how many were still being held. Hashemi's office said only three were arrested.

Hashemi's Iraqiya bloc, meanwhile, said it would boycott cabinet to protest Maliki's "dictatorship", after earlier saying it was suspending its participation in parliament.

"Iraqiya has decided today to boycott sessions of cabinet," Deputy Prime Minister Saleh al-Mutlak, who Maliki said over the weekend should be sacked, told AFP.

"This decision is based on the deterioration of the political process, and to ensure that the country will not head towards a catastrophe if Maliki's dictatorship continues."

Iraqiya, which holds 82 seats in the 325-member parliament and controls nine ministerial posts, has not pulled out of the national unity government.

Mutlak said the televised confessions were "political" and added that Iraqiya did "not recognise them".

The deputy premier, who was accused of being a supporter of Saddam Hussein's outlawed Baath party in the run-up to the 2010 elections that he was barred from standing in, told his own Babiliyah television channel this month that Maliki was "worse than Saddam Hussein."

Lawmakers are due to consider Maliki's request to fire Mutlak on January 3, a parliament official said.

Massud Barzani, president of Iraq's autonomous Kurdish region, earlier called for urgent talks to prevent the "collapse" of the country's national unity government, warning "the situation is headed towards deep crisis."

"The ruling partnership has become threatened," added Barzani, who in November 2010 hosted a meeting of Iraq's leaders at which the foundations of the national unity government were laid, ending months of impasse following elections in March that year, with a cabinet eventually named December 21.

He did not propose a date for the meeting in Monday's statement.

Hashemi's office, meanwhile, complained of "intentional harassment" in the form of a security force blockading his home for several weeks, as well as other incidents.

Iraqiya, which garnered most of its support from the Sunni Arab minority and emerged with the most seats in March 2010 elections, was out-manoeuvred for the premiership by Maliki who, after finishing second in the polls, struck a deal with another group to broaden his power base and lead the government.

The political party loyal to anti-US Shiite cleric Moqtada al-Sadr lamented that the timing of the crisis, after US troops completed their withdrawal from the country early on Sunday, suggested American forces had held the political system together.

"We do not want to send any wrong message to the world, after the withdrawal of the occupying forces, that the one who was controlling the issues in Iraq was the occupier," said Baha al-Araji, head of the Sadrist parliamentary bloc.