Iraqi Prime Minister Nouri al-Maliki has threatened to cut central government funding for his country's autonomous Kurdistan region if the Kurds pursued a drive to pipe oil exports to Turkey without Baghdad's approval.
The Kurdistan Regional Government (KRG) said last week that crude had begun to flow to Turkey and exports were expected to start at the end of this month and then rise in February and March.
"This is a constitutional violation which we will never allow, not for the [Kurdistan] region nor for the Turkish government," Maliki told Reuters news agency in an interview.
Turkey must not interfere in an issue that harms Iraqi sovereignty.
He reiterated Baghdad's insistence that only the central government has the authority to manage Iraq's energy resources.
"Turkey must not interfere in an issue that harms Iraqi sovereignty," Maliki said.
The central government and the Kurds differ over how to interpret the constitution's references to oil and how revenues should be shared. The Kurdish share was set at 17 percent after the US-led invasion in 2003, although the Kurds frequently complain that they get less than that.
Maliki said the Kurds had not met their budgeted commitment to export 250,000 barrels per day of oil, with the revenue going to the national treasury, but that so far the government had not retaliated by reducing their share of the budget.
"We did not do that as we did not want to affect the Kurdish people and we were looking to find acceptable solutions that would preserve national unity and the national wealth, but this year the situation looks difficult," Maliki declared.
In October 2012, the Kurds agreed to export an average of 250,000 bpd in 2013 if Baghdad paid the operators in the region.
As the wrangling went on, the Kurds stopped pumping oil via the Baghdad-controlled pipeline to Turkey, instead exporting smaller quantities by truck and taking the revenue directly.
Kurdistan, which enjoys a high level of autonomy from Baghdad and has its own security forces, government and flag, has also drawn Baghdad's ire for signing contracts with foreign energy firms without its approval.
In addition to disputes over natural resources, the long-standing ambition of Kurdish leaders to incorporate other historically Kurdish-majority areas into their autonomous region, against Baghdad's strong opposition, is another major point of contention.