Red Bull team principal Christian Horner says he expects the controversial independent customer engine proposal to be tabled again because the manufacturers will not meet criteria aimed at lowering costs before this month's deadline.

Last October, the FIA and the commercial rights holder raised the idea of introducing an independently developed customer engine using an alternative specification in an effort to circumnavigate the high costs and limited availability being offered to satellite teams by Mercedes, Ferrari, Renault and Honda.

However, the plan - which received support from Red Bull after it was unable to source an alternative to its Renault power for 2016 -, was shelved when manufacturers were tasked with meeting four criteria to reduce costs, simplify specifications, guarantee a supply and improve the noise as a compromise.

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A deadline of April 30th has been set, but while the manufacturers have indicated some confidence in meeting this, Horner said during the Chinese Grand Prix they are in fact 'nowhere near' reaching a satisfying agreement.

"Jean Todt set a criteria of 4 deliverables that Toto Wolff, representing the engine manufacturers was charged with going off to achieve. And the four things were: a reduction in price to 12 million euros from next year, and the availability of those engines of supply, power convergence to within plus or minus 2 per cent and to address the noise.

"All four to date haven't been met. So I think it's going to be an interesting discussion at the next strategy and Formula 1 commission meetings as to what the next steps of the FIA and the promoter will be to that."

Based on the original stipulation set out to the manufacturers, Horner says this should mean the independent engine proposal must be raised again.

"I think the FIA need to decide what they want because they made it clear previously that the independent engine was tabled, it was removed from the table on the basis of these things being offered. If they're now not available - if prices aren't going to come down, convergence isn't going to happen, supply isn't going to be restricted - then the criteria hasn't been fulfilled.

"How else are you going to deal with price affordability and availability? Convergence? It's still a major, major issue. The racing is good at the moment but we've still got this underlying issue that needs to be addressed. It's going to be interesting. It's not something that's going to be finished in a week."