Series bosses have conceded that the proposed rules will have to change in the wake of the decision of Porsche, which helped conceive the regulations, to withdraw from P1 at the end of this season.

WEC boss Gerard Neveu said: "The 2020 LMP1 rules will be substantially altered from what was announced at the Le Mans 24 Hours.

"But the Automobile Club de l'Ouest and the FIA [which jointly write the rules] are absolutely certain that technology and hybrid systems must keep their place in endurance racing, although not at any cost."

ACO sporting director Vincent Beaumesnil explained that there was "a clear target for a much lower budget to run a hybrid to make it easier for any manufacturer to join".

The next LMP1 rules cyles will now come into force at the start of the 2020/21 season after the WEC's switch to a winter-season format straddling two calendar year.

Zero-emissions kilometre plan abandoned

The zero-emissions requirement for factory P1 hybrids to complete one kilometre on electric power after each refuelling stop will be abandoned.

Neveu revealed that "main axis of the new technical regulations will be announced in the next few weeks".

He insisted that there was "real interest from certain manufacturers but under certain conditions".

"The question is the level of the hybrid; we have to leave space for hybrids, but the question is what kind of hybrid," he explained. "You can make a hybrid for less cost, for sure."

Peugeot, which was part of the rule-making process for 2020 along with Porsche and Toyota, is understood to have lobbied for a lower level of technology and a lower-cost entry point.

No DPi switch

Neveu also ruled out the WEC switching to a set of regulations similar to the LMP2-based Daytona Prototype international (DPi) rules introduced for this season in the IMSA WeatherTech SportsCar Championship in North America.

He suggested that the series had to be "respectful and correct" to manufacturers such as Toyota, as well as privateers like Ginetta and BR Engineering/Dallara working on new P1 projects.

New rules put in place for independents ahead of the start of this season were announced with a stability period up to the end of 2021.