"The officials in the central government who refuse to admit these contracts are failures who could not give to Iraq what we give to our people in Kurdistan," Massud Barzani said in a speech in Kurdish regional capital Arbil.

"They want us to be like them."

He continued: "The problem is not whether these contracts violate the constitution or not, but that they (central government officials) do not want the region to develop."

Barzani did not explicitly name any of the officials he was referring to.

The central government in Baghdad and Kurdistan regional authorities have been locked in a prolonged dispute over oil contracts with foreign energy firms.

The Kurdistan region has signed around 40 contracts with international companies on a production-sharing basis without seeking the express approval of the central government's oil ministry.

The federal oil ministry, meanwhile, has awarded energy contracts to international companies on the basis of a per-barrel service fee. It has also refused to sign deals with any firm that has agreed a contract with Kurdistan.

That refusal was put in the spotlight in October, when Kurdistan inked a deal with ExxonMobil to explore six areas of the region. The US firm had previously signed a contract with Baghdad to ramp up production at the West Qurna-1 field, Iraq's second-biggest.

Iraq has said the oil giant must choose between the two contracts.

Baghdad has also yet to approve an oil and gas law that would regulate the sector, with proposals languishing for several years.