SAO PAULO (Reuters) - Former world champions Red Bull have lodged their entry to next year's Formula One championship after earlier threats to withdraw unless they secured a competitive engine supply.
"We've entered the world championship so as long as we sort our engine predicament out, absolutely we'll be there next year," team principal Christian Horner told Sky Sports television at the Brazilian Grand Prix on Friday.
Red Bull's motorsport consultant Helmut Marko meanwhile told Sky Germany that both Red Bull Racing and Toro Rosso would be competing in 2016 in what would be a transition year.
Red Bull have yet to announce an engine deal but all the signs are pointing to an agreement with current suppliers Renault after exhausting all other options.
Mercedes have refused to provide engines while Ferrari are willing only to supply sister team Toro Rosso with year-old units.
Honda, whose reliability and performance is worse than Renault's, have expressed an interest but partners McLaren have a veto and are resolutely against.
"All I can tell you is we're homing in on something and as soon as we've got something to announce then you'll be at the top of the list," said Horner.
He would not be drawn on whether Red Bull, who earlier this season sought termination of their Renault deal despite it still having a year to run, were likely to use the French units as a basis to work on in-house.
"As soon as we've got something to say, we'll let you know. Anything else at the moment is just speculation," he said.
Australian driver Daniel Ricciardo welcomed the clear sign of progress.
"It is nice to know," he told reporters. "I always had faith we would (be competing next year), but it is the first step towards a better 2016, so it is good news.
"I feel between now and Abu Dhabi we will hear something."
Red Bull's chief engineer Paul Monaghan said separately the team would still be able to make the first pre-season test of 2016 despite the late engine decision.
"We are working towards a deal and if one can be achieved, then that will be announced in time but we will still make it, don’t worry," he said.
(Writing by Alan Baldwin in London, editing by Greg Stutchbury)