Iraq's Shia-led government has issued an arrest warrant for Tareq al-Hashimi, the country's vice-president and most senior Sunni official, on "terrorism" charges relating to alleged links to assassinations of government officials.
Adil Daham, a spokesman for Iraq's interior ministry, told reporters about the warrant on Monday, and state-run television aired what it characterised as confessions by alleged "terrorists" linked to Hashimi.
The men, who were said to have worked as bodyguards for Hashimi, said he had paid them to kill officials at several government ministries as well as Baghdad police officers.
The move, a day after the last US combat troops left Iraq to bring a formal end to the country's nearly nine-year war, signalled a sharp new escalation in sectarian tensions that drove Iraq to the brink of civil war just a few years ago.
Hashimi left Baghdad on Sunday for the semi-autonomous Iraqi region of Kurdistan, in a move that appeared to be motivated by hopes that Kurdish authorities would not turn him in. Investigative judges banned him the same day from travelling outside of Iraq.
Since the 2003 US-led invasion that toppled Saddam Hussein and his Sunni-dominated Baath party, the Sunni minority has constantly complained of attempts by the Shia majority to sideline them.
Hashimi is one of the leaders of the Sunni-backed political bloc Iraqiya, which has just suspended its participation in parliament in protest over the control of key posts by Nouri al-Maliki, the Shia prime minister.
Al Jazeera's Omar al-Saleh, reporting from Baghdad, described the recent events as a "political crisis".
"The government says this has nothing to do with the US withdrawal, that this has nothing to do with the prime minister consolidating his grip on power," our correspondent said.
"However, members of al-Iraqiya bloc, which Hashimi is a member of, say ‘No, [Maliki] is trying to be a dictator’."
Politicians said on Sunday that parliamentary officials had received Maliki's request overnight for a vote of no confidence against Saleh al-Mutlaq, a Sunni deputy prime minister and another leader of the Iraqiya bloc.
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Mutlaq is Iraq's second-most senior Sunni politician, after Hashimi. The Iraqiya bloc is a secular group backed by many Sunnis, which joined Maliki's unity government despite persistent complaints of being marginalised.
"The prime minister told us that he cannot work with Mutlaq any more ... If this will affect the work and the performance of the cabinet then we will be with him," said Amir al-Kinani, a parliamentary deputy from a Shia bloc.
Iraqiya deputy Ahmed al-Alwani accused Maliki's authorities of carrying out "political targeting", using the security forces and justice system against political opponents.
"There must be a way of dealing with these issues, without replacing the celebration of the US withdrawal with the
politicisation of security matters to target political rivals," he told the Reuters news agency.
A White House spokesman said the Obama administration had expressed its concerns to all of the parties involved regarding the issuing of the warrant.
"We are urging all sides to work to resolve differences peacefully and through dialogue in a manner consistent with the rule of law and the democratic political process,'' Jay Carney said.
PJ Crowley, former US state department spokesman, told Al Jazeera: "The optics and timing [of the arrest warrant] are highly suspect and are likely to make a challenging political environment very poisonous".
"Politicians need to lead the country together," he said. "Ultimately the Sunni, Shia and Kurds will have to be represented and function within the government".
Iraqiya narrowly won the most seats in last year's parliamentary election, but Ayad Allawi, the leader of Iraqiya. was outmanoeuvred by Maliki, who kept the prime ministerial post after winning key support from Shia parties.
For more than a year now, Maliki has effectively controlled the interior and defence ministries, which oversee the police and military, while conflicts between Sunni and Shia politicians have delayed the appointment of permanent ministers.
The dispute is a reminder that the US left behind an Iraq still rife with sectarian division. Iraqiya officials have warned they could take a further step if the bloc's demands are not met, pulling their seven ministers out of Maliki's coalition government.
According to our correspondent, the threat of a cabinet walkout has many Iraqis concerned the country is returning to a phase of political impasse.
"If that step is taken, this fragile government will be brought to a standstill. The people on the street fear this because it will affect their daily lives," he said.
In the last years of the US presence, Washington worked hard to keep Sunnis inside the political process to prevent it from unravelling.
Iraq's power-sharing government splits the presidency, the prime minister's post, two vice-presidencies and two deputy premierships among Shia, Sunni and Kurdish blocs. But Sunni politicians complain they are kept out of decision-making.