Iraq’s top court will begin hearings in May on the legality of oil exports from Kurdistan, which are at the centre of a row between the semi-autonomous region and Baghdad.

The oil dispute is the main hurdle to normalising relations between the central government and the Kurdistan Regional Government (KRG) of northern Iraq which conducted an October referendum on independence despite Baghdad’s opposition.

The Supreme Federal Court said in a statement on Monday it has asked to hear the opinions of officials including the central government’s prime minister, oil minister and finance minister, in addition to the KRG’s prime minister, on May 6.

Iraqi oil minister Jabar al-Luaibi had asked the court to issue a ruling that bans independent oil exports from the KRG, which started in 2014, through a pipeline across Turkey.

The KRG says the Iraqi Constitution recognises the legality of its existence and contains no article specifically forbidding it from developing oil resources on its territory.

International energy firms including Exxon Mobil, DNO, Dana Gas, Rosneft and Genel are among companies with agreements with the KRG to operate in the Kurdistan region.