BAGHDAD: Iraq has executed 21 prisoners convicted on terrorism charges and links to Al Qaeda, the Justice Ministry said Wednesday, setting off fresh criticism from a human rights expert over Baghdad's insistence on enforcing capital punishment.    

The prisoners were executed by hanging in the Iraqi capital on Tuesday, according to a statement posted on the ministry's website. All the convicts were Iraqi Al Qaeda operatives who were involved in bombings, car bomb attacks and assassinations, the statement said.

The hangings brought the number of prisoners executed in Iraq so far this year to 50, according to Deputy Justice Minister Busho Ibrahim. The latest group was the biggest this year, Ibrahim added.

According to the London-based Amnesty International, Iraq ranked fourth among the top five executioners in the world in 2011, after China, Iran, Saudi Arabia and the US Last year Iraq executed 129 people, triggering concerns among rights groups over whether defendants had received fair trials.

After the US-led invasion in 2003, coalition officials suspended Iraq's death penalty, but it was reinstated in 2004 by Iraq's transitional government. Since 2005, Iraq's government has executed 422 people, including women and foreigners convicted on terrorism charges.

Erin Evers, a Middle East researcher at Human Rights Watch, said the number of those executed and the timing of the latest announcement were cause for concern. On Saturday, Iraqis vote in local elections, the country's first vote since the withdrawal of the last US forces in December 2011.

The country has seen intensifying violence in recent weeks, some of it directly related to the elections, in an apparent attempt by insurgent to derail the voting.

On Monday, at least 55 people were killed in a wave of bombings and other killings across the country.

''The fact that this they announced this huge number (of executions) just after the attacks and just before elections is raising questions about what their motives are,'' Evers told The Associated Press in a phone interview.

Nine people were killed and 32 were wounded in four separate attacks in Iraq on Wednesday.

In one attack, gunmen in two SUVs opened fire early in the morning on a military checkpoint in Baghdad's western suburb of Abu Ghraib, killing two soldiers and wounding five, a police officer said. Another police officer said a parked car bomb went off shortly afterward in another part of Abu Ghraib, killing two civilians and wounding six people.

Around noon, a parked car bomb exploded in a commercial area in Baghdad's western neighborhood of Jihad, killing three civilians and wounding 12.

In a Baghdad southeastern suburb, a Sunni lawmaker escaped an assassination attempt when a roadside bomb hit his convoy. Three of his guards were wounded.

In the western Anbar province, police said a bomb attached to a car exploded in a parking lot near the main Sunni protest area on a highway near the provincial capital, Ramadi, killing two people and wounding six others.

Members of Iraq's Sunni minority have been staging weekly rallies to protest perceived second class treatment by the Shia-led government.

After sunset, police said gunmen assassinated a judge, Maarouf Ahmed, in a drive-by shooting in the western city of Fallujah.

Medical officials confirmed the causalities in Wednesday's attacks. All officials spoke on condition of anonymity because they were not authorized to talk to reporters.