The championships have shared events since 2001 but both could have separate calendars next season over a disagreement regarding the length of the FIA GT races.
Stephane Ratel, boss of FIA GT promoter SRO, has confirmed to Autosport-Atlas that he is making plans for his series to run separate from WTCC next season.
Most FIA GT races are three hours long, however WTCC promoter KSO and broadcaster Eurosport are keen for them to be reduced to two hours to maximise TV time and reduce costs to competitors and circuits.
Ratel believes he cannot meet KSO demands. He told Autosport-Atlas: "They want us to reduce our race length which is not possible for our drivers and teams. This would not work with how our teams decide on their driver's budgets according to car time and speed. A driver only competing for 40 minutes in the middle stint of a race is unacceptable.
"We cannot agree to this. A two-hour race would open up the event to sprint car, which is against the spirit of endurance racing.
Despite pushing ahead with plans for a separate series, Ratel said he is still open to reconciliation, with last ditch talks planned for the end of August.
"Naturally my preferred option is to stay with WTCC," Ratel added, "however, we will push ahead for a separate series. Things are not final and if we can sort things out later then fine.
"I'm not worried by this and FIA GTs can stand alone, and they have before. We have other series such as the LMES and British F3/GT that we have made a success on their own."
Another bone of contention is the current three-day format of the meetings. KSO would like them to be reduced to from three to two days to reduce the costs of having to be present on the first day, which includes no track activity for the WTCC.
An FIA WTCC spokesperson told Autosport-Atlas: "Currently the World Touring Car paddock has to assemble on Thursday with the FIA GT paddock because they start a day earlier.
"We want them to have shorter races and shorter meetings. If they accept this then fine. The plan was to continue together for another year at least but we could separate."
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