"These contracts will be suspended until the oil and gas law is passed," said Abbas al-Bayati, member of parliament for the Supreme Islamic Iraqi Council (SIIC), one of Iraq's most powerful Shiite factions.

"When companies or countries sign these contracts, they have to behave according to the law of the country," Bayati added.

The autonomous Kurdish regional government in northern Iraq has signed 15 exploration and export contracts with 20 international companies since it passed its own oil law in August, infuriating the Baghdad government.

Shahristani has angrily denounced the Kurdish authorities for signing the contracts before the national parliament approves a new oil and gas law, declaring them "illegal" and "null and void."

The Kurdish authorities have hit back sharply, telling the minister he is exceeding his authority and that he should mind his own business.

"His statements will not affect our contracts with foreign companies," regional prime minister Nechirvan Barzani said last week. "The (regional) government will continue with the contracts and they will be implemented."

The heated row comes despite Prime Minister Nuri al-Maliki's wooing of Kurdish parties in an attempt to salvage his embattled government, which has been hit by walkouts by Sunnis and radical Shiite cleric Moqtada al-Sadr's political bloc.

In August, Maliki brokered a new political alliance between his Dawa party and Vice President Adel Abdel Mahdi's SIIC, President Jalal Talabani's Patriotic Union of Kurdistan and Kurdish regional president Massud Barzani's Kurdistan Democratic Party in a bid to shore up his government.

Despite generally good relations within the new coalition, SIIC politicians this week were quick to round on the Kurdish authorities.

"These contracts are illegal, and must pass through the central government to be approved in accordance with the Iraqi constitution," said Zuhair al-Hakim, a SIIC official in the Shiite holy city of Najaf.

"The origin of this dispute is that the Kurdistan Regional Government approved its own oil and gas law before the national law has been passed."

The Sadr movement too came out against the Kurdish deals.

"We believe the central government should be in charge of such agreements," said Liwa Sumaysim, head of the political bureau of the Sadr movement, also based in Najaf.

"We reject the autocratic way in which these contracts were signed and we ask the government to continue to stand against it too," Sumaysim added.

Another Shiite party, Al-Fadhila, was less strident.

"It would be better if the riches were in the hands of the central government as the only party that can guarantee national unity," said Nadim al-Jabiri, Al-Fadhila's political advisor.

Kurdish MP Mahmoud Othman said the dispute is complex and should be put to the country's constitutional court.

"It's a complex issue. The Kurdistan Regional Government says that the contracts they signed are valid, while the central government says they are not," said Othman.

"I think it is best that these contracts are submitted to the constitutional tribunal which will decide if they are valid or not," he said.

Iraq's oil and gas bill is stalled in the national parliament amid bitter differences between rival factions.

When approved, the new law will open up Iraq's long state-dominated oil and gas sector to foreign investment and will stipulate that receipts be shared equally between Iraq's 18 provinces.