The United Nations on Thursday, April 18 called on Iraq to suspend use of the death penalty after authorities executed 21 people on the same day following their conviction on terrorism charges, according to Reuters.

The high rate of executions, making Iraq the world's most prolific user of the death penalty after China and Iran, has put the country under fire from human rights groups. So far 32 people have been executed in Iraq this month.

Executions are a sensitive issue for Iraq's Shi'ite Prime Minister Nuri al-Maliki whose government faces rallies by thousands of Sunni Muslims against what they see as marginalization of their sect.

"I regret that repeated calls of the United Nations to suspend the implementation of death sentences were not heard," U.N. representative Martin Kobler said. "I urge once again the Iraqi government to immediately suspend all pending death sentences and to apply without delay the moratorium."

The justice ministry said 21 people had been executed on Tuesday for crimes linked to al Qaeda, including five accused of trying to attack Maliki's convoy.

An Amnesty International report this year said that since the Iraqi government restored the death penalty in 2005 at least 447 prisoners had been executed, including Saddam Hussein, his main associates and suspected members of armed groups.