Federal Iraqi forces seized control of key oilfields in the disputed province of Kirkuk earlier this week, CNBC reports.

Kurdish forces peacefully withdrew from the Kirkuk oilfields. The oilfields have a current production capacity of approximately 250,000 barrels a day (b/d) of crude oil, according to the Kuwait Times.

The fields seized by the federal forces included the Bai Hasan, Avana, Baba Gurgur, Jambur, and Khabbaz oilfields, an Iraqi military official told the Saudi Gazette. Iraqi oil officials told the newspaper that the oilfields were operating as normal.

The areas were previously held by Kurdish peshmerga under the authority of the Kurdish Regional Government (KRG). In 2014, as the Islamic State conquered large portions of northern Iraq, Kurdish forces moved into strategic locations adjacent to their territory, preventing many important oilfields from falling into the hands of the militant group.

Kirkuk and its oil have long been a point of contention between the KRG and the central government in Baghdad. 

The military operation is part of a campaign by the federal government to retake areas controlled by the KRG outside their legally recognized semiautonomous areas in northern Iraq, according to the Saudi Gazette.