It was confirmed on Wednesday morning that the German manufacturer will be ending its LMP1 programme at the end of the 2016 season after 18 years at the top level of endurance racing.

The announcement means only Porsche and Toyota are signed up in WEC's top division for 2017 and beyond, raising the prospect of only having four LMP1-H entries next season.

In its response, series organisers paid tribute to Audi's integral role in supporting the nascent championship in its early years, while pointing to the fact that other manufacturers - including BMW in the GTE category from 2018 - will be joining in future.

“We understand this decision [by Audi], although obviously we regret the departure of a major player in the WEC," said series boss Gerard Neveu.

"Audi has been involved in endurance racing for 15 years, and more particularly in the first five seasons of the WEC.

“Today we spare a thought first for everyone at Audi Sport and at Team Joest. We offer them our admiration and gratitude for their extraordinary sporting performances in the WEC since 2012."

He added: "In a week’s time, in Shanghai, Porsche and Toyota will be battling on track for the 2016 LMP1 world title, as Ferrari and Aston Martin will be for the GTE title.

“One manufacturer is leaving, others will soon be arriving. This is the life of a championship.”

Cost-cutting and hydrogen cars on agenda

Pierre Fillon, president of the Automobile Club de l'Ouest (ACO), also said that reducing the costs of competing in the LMP1 class and finding a way to accommodate hydrogen-fuelled cars in the rulebook will be core aims for sportscar racing moving forward.

"To reduce costs for manufacturers is a major focus for the ACO, in partnership with the FIA," he said.

"Furthermore, these two organisations have clearly set the course for the coming years: stay at the forefront of innovation while offering the best possible platform for new technologies in preparation for the cars of tomorrow.

“Hybrid technology and electric motors are already part of our daily lives in endurance racing. The changes to the technical regulations towards hydrogen-electric power responds straight away to the energy requirements of this new era."

Toyota: We're here to stay

Meanwhile, Toyota moved to confirm that Audi's decision to exit will have no bearing on its future involvement in WEC or the Le Mans 24 Hours, which it infamously came so close to winning for the first time this year.

A team spokesperson told Motorsport.com: "Toyota Gazoo Racing has noted with regret the announcement today by Audi regarding its future in the FIA World Endurance Championship (WEC).

"Audi has been a strong and sportsmanlike competitor since Toyota’s return to endurance racing in 2012 and we appreciate their role in establishing the WEC as one of the fastest growing, most innovative championships in motorsport.

"Today’s announcement has no affect on Toyota’s position in WEC. We are preparing for 2017 when we will return with the target of winning the Le Mans 24 Hours and the World Championship."