Renault says Red Bull has to make a decision over its 2019 engine supply before the French Grand Prix next weekend.
Red Bull has still yet to decide whether it will continue with Renault for a further two seasons or switch to Honda. Both manufacturers brought upgraded engines to the Canadian Grand Prix giving Red Bull the opportunity to assess and compare them.
Renault agreed to push back the FIA's original deadline of May 15 and now that Red Bull has had the opportunity to compare both power units in Canada, managing director Cyril Abiteboul says it needs to make a decision in the coming days.
"We're trying hard, but that must be under conditions that are acceptable to us, starting with the timing," Abiteboul said. "I don't want to start mentioning a date, otherwise, you'll start calling me that day.
"I have a date, they know the day, but we are not talking about Austria. Austria, we won't be here, and they will be talking directly to Honda. They wanted an offer, we've made an offer, that offer has to be accepted in the next few days."
Renault is keen to remain in partnership with Red Bull, claiming that a move to Honda would cost it the chance of winning a championship before 2021. Abiteboul has stressed the need for a decision to be made quickly, but Red Bull wants until its home race in Austria to decide.
"I guess they have all the information that they need now. I don't see why they are going to further delay the decision," Abiteboul added. "As per the regulations, [the deadline] was May 15, and then we accepted to extend that a little bit on the back of 12 years of good collaboration.
"But past a certain point, the offer we made, and that they requested, will not stand. It was Montreal that they wanted to wait for: our new spec, Honda's new spec. They have all the information, I see no absolutely no reason to delay that any further."
Abiteboul ruled out waiting for Red Bull to decide in Austria as it needs to order parts and components in advance for its 2019 engine.
"I don't think so. It's simply because we need to source the components.''