0816 GMT April 20, 2019
A statement said the court "rendered a decision declaring unconstitutional the referendum held on September 25, 2017 in Iraqi Kurdistan... and cancelling all the consequences and results that resulted," AFP reported.
Monday's legal move was the latest stage in a crisis sparked by the referendum, which resulted in a resounding "yes" vote for departure in the Kurdish area.
Responding to the court's decision, the Kurdistan region's prime minister, Nechirvan Barzani, said on Monday: "The federal court reached its verdict on independence without the Kurdistan's regional government's input, thenational.ae reported.
"The rights of Kurds are enshrined in the constitution, and we seek the implementation of this constitution to resolve our issues with Baghdad," he said.
He added: "If the Iraqi constitution was fully implemented, we would have no issues with Baghdad."
Barzani, speaking at a news conference in Erbil, said that Baghdad's non adherence to the constitution led Kurdistan to hold referendum on independence.
"Stability in Iraq cannot be achieved without implementing the constitution. If Baghdad and the international community want to commit to Iraq's integrity, then the Iraqi constitution must be applied," he said.
Barzani called on Baghdad to not "be selective in its application of the constitution".
"We need a third party present during talks between Erbil and Baghdad to ensure the Iraqi Constitution is respected and implemented," he said.
Last month, the UN Security Council urged the Iraqi government and regional leaders in Kurdistan to set a timetable for talks to end the crisis.
The world body's appeal came after Baghdad dismissed an offer from Iraqi Kurdish leaders to freeze the outcome of the referendum and hold talks.
Rejecting the freeze offer, Iraqi Prime Minister Haider al-Abadi instead demanded the annulment of the vote.
Last week, as the deadline announced by the Supreme Court for its decision on the constitutionality of the referendum approached, the Kurdistan government said it "respected" the decisions taken by Iraq's highest court.
It also said it respected a previous decision insisting on Iraqi unity, which could be a basis for dialogue.
Parliament in Baghdad is currently reviewing the federal budget for the coming year, including the allocation for the autonomous Kurdish region.
September's referendum was initiated by then Kurdish leader Massud Barzani, for whom the repercussions were severe.
Barzani at the beginning of November announced he was stepping aside, having lost almost all of the territory disputed between Kurdish capital Arbil and Baghdad.
The Kurds also lost all of the oil resources in Kirkuk Province that could have ensured the viability of a hypothetical Kurdish state.hetical Kurdish state.