Double world champion Fernando Alonso said on Thursday he would not stick around in Formula One if the calendar grew to 25 races a year.

The 35-year-old, whose future at under-performing McLaren is already uncertain beyond this season, was asked at the Canadian Grand Prix if it was true he had told Spanish television he would retire rather than do such a number of races. “Yes,” he replied.

“I started when the calendar was 16 races, plus the tests,” continued the Spaniard. “Now we keep on increasing the races year after year and I think we are in a number that is quite demanding already.

“The preparation, the sponsor events, the tests, the commitments you have plus 20, 21 races, I think is already enough.

“I consider that a good quality of life is more important than to do more seasons in F1 – so if the calendar stays between 20-21... I’ll be happy to continue. If it’s increasing, like NASCAR, that they have 40 or 50 races, it’s not for me.”

The 2017 calendar has 20 races but next year will see it grow to 21 with France and Germany returning and Malaysia leaving.

Liberty Media, Formula One’s new American owners, have big plans to reshape the sport and are targeting new venues in key markets, including another race in the United States and Asia.

“We want to work in partnership with our teams in terms of determining where we go, but our view is that we’d like to go above 21 (races),” Formula One’s commercial managing director Sean Bratches told Reuters last week. He did not specify an upper limit.

McLaren’s executive director Zak Brown said that he would welcome a second race in the United States, another in China, one in South Africa and ideally a return to India although that looked unlikely.

“We still aren’t where we need to be in China. You could have a race in Beijing and Shanghai and I don’t think you’ve saturated Asia,” he said.

He warned, however, that the sport needed to preserve its exclusivity. And it also depended on the venues.

“If we are at 21 (races) and you are talking that the 22nd can be New York, then yes! If you told me the 22nd was Nebraska, no,” he said.

Piecing together the calendar is never simple, with many of the constituents looking for different things and concerned about budgets and the impact on team staff.

Triple world champion Lewis Hamilton said he agreed with Alonso but the Mercedes driver stopped well short of saying he would leave if the calendar continued to expand.

“I understand what Fernando is saying and I tend to agree with it,” said the Briton.