Human Rights Watch on Monday urged US President Barack Obama to prioritise critical human rights issues during his Tuesday meeting with Iraq's Prime Minister Hayder Al-Abadi.

"US President Barack Obama should place Iraq’s abusive sectarian militias at the top of his agenda for his meeting with the Iraqi prime minister," HRW said in a letter to the president.

Al-Abadi is to meet with Obama in Washington to discuss the ongoing battle in Iraq against the Islamic State militant group.

Al-Abadi is seeking greater military support. "Number one is a marked increase in the air campaign and the delivery of arms," he said at a press conference Monday, AFP reported.

The rights group is calling on Obama to make clear that US security assistance to Iraq will be linked to the Iraqi government’s progress in reigning in pro-government militias which have, the group says, committed serious abuses against civilians in areas retaken from the Islamic State.

The Islamic State group poses a real threat in Iraq but there is "no reason to pretend that paying lip service to human rights is an adequate response to the militia abuses,” said Joe Stork, deputy Middle East and North Africa director at Human Rights Watch.

“Obama needs to send a clear message that US support for Iraq requires more serious efforts by Baghdad to protect all Iraqis’ basic rights," Stork said.

On 18 March, the US-based rights watchdog released a statement declaring that the Iraqi volunteer fighters and Iraqi forces were destroying and burning Sunni villages after IS militants had retreated.

On that statement the HRW called on the Iraqi government to restrain the militias to avoid "paving the way for such abuses."

HRW reported that according to eyewitnesses the Iraqi militias "looted property of Sunni civilians who had fled fighting, burned their homes and businesses, and destroyed at least two entire villages."

According to the letter, a senior US official expressed his concerns over the militias' abuses of Sunni civilians, but "providing more weapons by the US to Iraqi government is weakening such concerns and criticism."

Obama should ask the Iraqi premier to hold commanders of the militia and anyone who is responsible for such crimes to account via a judicial process, HRW argues, and should call for the Iraqi government to amend the terrorism law and develop a comprehensive plan that includes measures to assist displaced people to return home safely.

"The administration should ensure that the US embassy in Baghdad has sufficient personnel and resources to closely monitor how US arms and training are being used," Human Rights Watch said.

In the meantime, Al-Abadi said at the press conference Monday that the weapons sent by US have already seen an increase, "but we want to see more."