BAGHDAD (Reuters) - The Iraqi government has dismissed a call from U.S. Secretary of State Rex Tillerson for Iranian-backed paramilitary units that helped Baghdad defeat Islamic State to end operations in Iraq.

Iraqi Prime Minister Haider Al-Abadi attends a meeting with Saudi Arabia's King Salman bin Abdulaziz Al Saud and U.S. Secretary of State Rex Tillerson in Riyadh, Saudi Arabia October 22, 2017. Saudi Press Agency/Handout via REUTERS

Speaking after a meeting on Sunday with Iraqi Prime Minister Haider al-Abadi and Saudi Arabia’s King Salman, Tillerson said it was time for the Iraqi Popular Mobilisation forces and their Iranian advisers to “go home”.

Washington, which backed Baghdad against Islamic State, is concerned Iran will use its expanded presence in Iraq and in Syria to expand its influence in the region.

But Abadi showed unwillingness to meet Tillerson’s demand.

“No party has the right to interfere in Iraqi matters,” the statement from his office read. It did not cite the prime minister himself but a “source” close to him.

Trained and armed by Iran, the Iraqi Popular Mobilisation forces often supported Iraqi government units in the fight against the militants who were effectively defeated in July when a U.S.-backed offensive captured their stronghold Mosul.

They are paid by the Iraqi government and officially report to the prime minister, but some Arab Sunni and Kurdish politicians describe these militias as a de facto branch of the Iranian Revolutionary Guards Corp.

Iraq’s Sunni neighbors, including Saudi Arabia, share Washington’s concerns over Shi’ite power Iran’s influence in Iraq, where the population is also predominantly Shi’ite.

But the office of Abadi, himself a Shi’ite, said the forces were under the authority of the Iraqi government. “Popular Mobilisation are Iraqi patriots,” it said in the statement.

The United States trained tens of thousands of Iraqi soldiers in the course of rebuilding the Iraqi armed forces and has over 5,000 troops deployed in the country, providing key air and ground support to the offensive on Islamic State.