Iraqi Prime Minister Haider al-Abadi said on Monday he had formally demanded the Kurdistan region suspend an independence referendum that regional neighbours and Western powers fear could undermine a campaign against Islamic State militants.
Turkey, which like Iran harbours fears of Kurdish separatism on its own territory, carried out military exercises at the Iraqi border. Iran warned of unspecified consequences if the Iraqi Kurds went ahead with their plans.
But the Kurdish leadership in northern Iraq showed no sign of flinching despite coming under intense international and regional pressure to call off the September 25 vote.
Kurdish forces have, with U.S. backing, been in the forefront of the battle against Islamic State in Iraq and Syria.
But the Kurdish involvement strains relations between Washington and Ankara.
The Iraqi Supreme Federal Court approved Mr Abadi's demand to consider "the breakaway of any region or province from Iraq as unconstitutional", his office said in a statement.
"The Supreme Court has issued the order to suspend organising the referendum set for September 25... until it examines the complaints it has received over this plebiscite being unconstitutional," the court said in a statement.
The court took the decision after it "reviewed requests to stop the referendum".
Court spokesman Ayas al-Samouk, told AFP: "We have received several complaints and this is why we decided to suspend the referendum."
A source in parliament said at least three lawmakers had filed complaints against the poll.
Neighbours Turkey and Iran, as well as the United States and United Nations, have pleaded for the autonomous Kurdish region of northern Iraq to settle its differences with Baghdad through negotiations rather than secession.
Iraqi Kurdish leader Massud Barzani has said a "yes" vote would not trigger an immediate declaration of independence but rather kick-start "serious discussions" with Baghdad.
Britain's Defence Secretary Michael Fallon said he would try to persuade Iraqi Kurdish leader Massud Barzani at a meeting later Monday to call off a controversial September 25 independence referendum.
"I will be this afternoon in Arbil to tell Massud Barzani that we do not support the Kurdish referendum," he said at a press conference in Baghdad.
"We are committed to the integrity of Iraq. We are working with the UN on alternatives to this referendum," he said before heading to the Iraqi Kurdish capital in the northern city.
Iraqi Kurds have announced a September 25 vote on the autonomous oil-rich region's independence in a poll that Baghdad has argued would be unconstitutional.
