The administration in the autonomous Kurdish region in the north of Iraq said on Wednesday that it had "not seen and approved the final text of the law".
"We hope that the cabinet is not approving a text with which the KRG (Kurdish Regional Government) disagrees because this would violate the constitutional rights of the Kurdistan Region," it said in a statement.
The Kurdish administration said it was uncertain which version of the law was approved on Tuesday, but Ali al-Dabbagh, an Iraqi government spokesman, said the latest text contained only linguistic changes to the February draft.
|"If it [cabinet] has agreed to the version that included material and substantive changes, the KRG rejects this document"|
Kurdistan Regional Government statement
"While the KRG is happy with the legal committee's language improvements and restructuring of the legal text, we reject its changes to the substance of the law," the Kurdish government said.
"If it [cabinet] has agreed to the version that included material and substantive changes, the KRG rejects this document. We have not been informed which text the Iraqi cabinet has approved."
It was unclear how many ministers were present at Tuesday's cabinet meeting, as six ministers from Muqtada al-Sadr's group and six ministers from the Sunni bloc are currently boycotting the government.
A number of foreign companies have already entered into contracts with the Kurdish regional government and many fear that the new law may lead to the termination of the deals.
In May, Hussein Shahristani, the Iraqi oil minister, said any contract signed before the adoption of law would be cancelled.
Leaders from Iraq's main Sunni Arab political bloc, the National Concord Front, also expressed concern over the latest bill.
"The Front did not receive any official information of the draft. We do not know anything about the latest copy which was endorsed by the cabinet," Ala Makki from the Iraqi Islamic Party said.
"If our brothers want to pass the law without the Front's opinion then it is their affair and it is up to them. We are not responsible for it."
Iraq's oil reserves are largely in the Kurdish north and the Shia south leading Sunni Arabs from the central and western regions to fear they could be robbed of the revenues from crude exports.