The most senior Catholic cleric in Iraq warned that Christians in his country face "liquidation" if the Iraqi government and the US military do not step-up protection for religious minorities in Iraq.

"We are the target of a campaign of liquidation, a campaign of violence," said Chaldean Archbishop Louis Sako, reported Agence France-Presse on Friday. "The objective is political."

Sako's comment comes after police reported earlier this week that seven Christians have been killed in separate attacks this month. Police found bullet-riddled bodies of seven Christians so far this month, with the latest body of a Christian day labourer found on Wednesday.

Since the US-led Iraq war in 2003, more than 200 Christians have been killed, dozens of churches bombed, and more than half the Iraqi Christian population has left the country, according to the archbishop.

He called on Prime Minister Nouri al-Maliki's Shiite Muslim-led government to act on repeated promises to protect Iraq's minorities.

"We have heard many words from Prime Minister Maliki, but unfortunately this has not translated into reality," he said. "We continue to be targeted. We want solutions, not promises."

Iraqi Christians, who have no powerful tribes or militias, are completely defenseless and entirely dependent on the government and the US military for protection against extremists, he said.

"We believe it is the responsibility of Americans who occupy our country to protect Iraqis," Sako said.

He noted that six Christians had recently been killed in less than a week in the northern city of Mosul, including three Christian men who were killed within 24 hours.

"These attacks are not the first," the senior cleric said. "Unfortunately, they will not be the last."

Sako, based in the northern city of Kirkuk, has overseen the Christian community in Mosul since the death of Archbishop Paulos Faraj Rahho in March. Rahho, the second most senior Catholic cleric in Iraq, was kidnapped by gunmen after Mass and found dead by the roadside in Mosul two weeks later.

"Those who carry out the attacks want to either push Christians out of the country or force them to ally with some political projects," Sako said.

But he called on Christians not to lose faith in the country, and stated that "Christians are true sons of Iraq".

Christians make up a disproportionate number of those fleeing Iraq as refugees to neighbouring countries. Although Christians make up only three per cent of Iraq's population, they account for nearly half of the refugees leaving the country, according to the UN High Commissioner for Refugees.

Christian leaders in Iraq are urging the Iraqi parliament to reinstate a law that would reserve a quota of seats for minorities in provincial council elections.

The Iraqi Parliament had recently dropped the clause in its new provincial election law, causing human rights groups and the UN special representative Staffan de Mistura to criticise the decision and demand lawmakers to reinstate Article 50.