An Iraqi judicial committee has issued an arrest warrant for vice-president Tariq al-Hashemi under anti-terrorism laws.
The warrant was issued after arrested bodyguards of Mr Hashemi reportedly accused him of links to terrorism.
He has been banned from leaving Iraq, and is said to be staying in in Kurdistan, a semi-autonomous enclave in the north.
State-run television has reportedly aired what it says are confessions by alleged terrorists linked to Mr Hashemi, a Sunni in the mainly Shia Arab country.
The move comes the day after US troops withdrew from the country and two days after the al-Iraqiya parliamentary bloc, which represents most of Iraq's Sunni Arab community, withdrew from parliament.
They have accused the Shia Arab Prime Minister, Nouri Maliki, of monopolising power, the BBC reports.
The president of Iraq's autonomous Kurdish region, Massoud Barzani, earlier called for urgent talks to prevent the "collapse" of the national unity government, warning that "the situation is headed towards deep crisis".