Iraq's vice president Tareq al-Hashemi, a critic of premier Nuri al-Maliki and one of the country's top Sunni officials, was handed a second death sentence in absentia on Thursday.

Defence lawyers for Hashemi, who has been abroad since charges of running a death squad were filed against him in December, protested they had not been informed of the sentencing hearing over a plot to murder a security official.

Hashemi has previously dismissed the charges brought against him by Maliki's Shiite-led government as politically-motivated.

"The central criminal court of Iraq issued a death sentence against Tareq al-Hashemi and Ahmed Qahtan, because he (Hashemi) urged his guards to put a bomb on a car belonging to an interior ministry officer," said judicial spokesman Abdelsattar Bayraqdar.

He did not give further details.

Qahtan, who is last known to have been in Turkey, is Hashemi's secretary and son-in-law.

Lawyers for Hashemi complained that they were not informed of the session and had been told that the next hearing was to take place on Sunday.

"They should have taken the decision in the presence of the defence lawyers," said Muayad al-Izzi, head of Hashemi's defence team. "They did not invite us, they did not call us. We were informed about it later."

Hashemi was first handed a death sentence for three murders in a hearing on September 9, the same day a wave of deadly attacks killed dozens of people nationwide.

He was originally accused of running a death squad in mid-December 2011 as the last US troops left the country.

Hashemi fled to Iraq's autonomous Kurdistan region, which declined to hand him over to the federal government, and then embarked on a tour that took him to Qatar and Saudi Arabia, and finally to Turkey.

Born in 1942, Hashemi became one of Iraq's vice presidents in April 2006, the same month his brother and sister were shot dead in separate attacks.

At the time, he was the head of the Iraqi Islamic Party, a group that was said to have connections to some elements of Iraq's Sunni insurgency following the US-led invasion of 2003.

Hashemi later joined Iraqiya, the secular, Sunni-backed bloc that won the most seats in 2010 parliamentary polls only to be outmanoeuvred by Maliki, who retained the premiership.

In the earlier trial that resulted in his first death sentence, the court heard testimony that silenced pistols were found in raids on his house and that of his son-in-law, while bodyguards and other officials said they were offered money or coerced to carry out attacks on his orders.

Requests by Hashemi's lawyers for high-ranking officials to testify as character witnesses on his behalf were rejected, and his lawyers walked out of one session after a judge refused to accept their evidence.