BAGHDAD — Iraq's highest court ratified death sentences on Thursday for three men convicted of a 2010 attack on a Syrian Catholic cathedral in Baghdad, the bloodiest attack on Iraqi Christians after the 2003 invasion.

Gunmen linked to Al-Qaeda seized hostages during Sunday mass at the Our Lady of Salvation church in Baghdad on 31 October 2010. Around 52 hostages and police were killed and 67 wounded in the attack, which ended when security forces stormed the church.

Al-Qaeda's Iraqi affiliate, Islamic State of Iraq, claimed responsibility for the attack.

"There are three convicted criminals. All of them are Iraqis and they were convicted based on the terrorism law," said Abdul-Sattar al-Birqdar, spokesman for the Supreme Judicial Council.

"The sentence is final and it will be sent to the presidency to issue a decree to the Justice Ministry to execute it."

Last week, UN High Commissioner for Human Rights Navi Pillay criticized Iraq for carrying out a large number of executions and questioned the fairness of its judicial proceedings. On Wednesday, Iraq executed 17 people.

While most of the sectarian fighting that followed the 2003 US-led invasion was between Sunni and Shia Muslims, attacks on Christians in Iraq have increased in recent years.

The brazen assault on Our Lady of Salvation struck fear into the Christian community, prompting hundreds of families to flee to Iraq's northern Kurdish region or overseas. Pope Benedict condemned the attack.

Iraq once had about 1.5 million Christians but the number has fallen sharply in recent years, according to church reports. Iraq's total population is estimated at about 30 million.

One of the alleged leaders of the church attack, Huthaifa al-Batawi, known as Al-Qaeda's "Emir of Baghdad," was killed in an attempted jailbreak last May, officials said.

Violence in Iraq has fallen sharply since the height of the 2006–2007 fighting between majority Shias and once dominant Sunni Arabs, but bombings and shootings by insurgents and militias remain a daily occurrence.