Red Bull's search for a 2016 engine partner has taken another blow with Bernie Ecclestone revealing McLaren CEO Ron Dennis has blocked Honda from supplying them.
The Milton Keynes-based squad are without an engine supplier for next year after they decided to end their relationship with Renault following a public fallout.
They initially turned to Mercedes and Ferrari, but both manufacturers said no and they have now also held discussions with Honda.
However, it appears to be a no-go with Ecclestone saying Dennis has vetoed any deal between Red Bull and Honda.
"At the moment it would appear Honda are happy to give them [Red Bull] an engine, and Mr Dennis thinks they shouldn't," he said. "When Honda came in the FIA said to them if we let you into Formula 1 you've got to supply three teams.
"But they said 'As we're a brand new company, we don't think we can do that', so it was said to them to supply one team for the first year, two for the second and three for third.
"So Honda has an agreement with the FIA and myself that allowed them into F1 on the basis of supplying one team for the first year, etcetera.
"But they somehow made a commitment to Ron he had a veto, and he doesn't want Red Bull. He believes they may be competitors.
"Ron has said definitely no [to a supply], as far as he's concerned, but I don't know if his veto will stand up or not."
Ecclestone admits he doesn't "blame" Dennis for saying no.
"I'm not blaming anybody. I said I'd tell you the facts and they are the facts," he said. "Red Bull could run Honda [engines] if Honda agreed, but they won't agree to avoid having an argument with Ron."
Red Bull decided to split from Renault as they were unable to provide fast and reliable engines, something which Honda has also struggled with this campaign, but Ecclestone admits he's not sure how much the Japanese manufacturer will improve next year.
"At the moment, but we don't know what next year's Honda is going to be like," he said.
Meanwhile, Honda boss Yasuhisa Arai doubts they would be able to supply Red Bull with engines next year.
""Realistically, it would be very difficult because it is late October."