Iran and Iraq have put Organization of the Petroleum Exporting Countries (Opec) on notice of substantial oil output increases to come, saying others in the producer cartel will need to give way to make room for them.

Speaking ahead of an Opec meeting, oil ministers for the two countries – rivals as the group’s second and third biggest producers after Saudi Arabia – said they were targeting 4 million barrels a day (mbpd), growth of about one mbpd a piece.

Neither country can expect to reach those goals any time soon, but both are keen to prepare the ground for special treatment should the  Opec need next year to negotiate a deal to curb supplies to keep oil prices above its favoured $100 a barrel.

Neither can raise output quickly enough to make waves at Opec meeting – ministers confidently predict no change in the group’s production cap of 30 mbpd.

“This looks like jockeying for position ahead of a potential need for a need for a structured output agreement in 2014,” said Bill Farren-Price of consultancy Petroleum Policy Intelligence.

­­A senior Gulf delegate said next June’s meeting might require Opec to consider supply cuts. More oil from Iran and Iraq, a recovery in output from fellow Opec member Libya and fast-rising US shale oil could tip the balance.

“Maybe we’ll talk about cuts in six months from now,” he said.