Formula 1's planned return of in-race refuelling looks set to be scrapped.
The measure was apparently agreed at the most recent meeting of the Strategy Group, as part of a package of changes designed to spice and speed up F1 for 2017.
But since the May 15 announcement, teams have "raised concerns", Germany's Auto Motor und Sport reports.
That is despite the majority vote at the Biggin Hill meeting, including the agreement of Bernie Ecclestone and the FIA.
But correspondent Michael Schmidt said that at the next Strategy Group meeting, "arguments against the reintroduction (of refuelling) will be put on the table".
Cost concerns are one issue, with the increase said to be EUR 1.5 million per team.
But Force India team manager Andy Stevenson insisted: "Everyone had agreed: if it really would improve the show, the extra costs would be justified."
Teams warned instead that refuelling will make races more predictable, limit strategy choices and lead to a reduction in overtaking.
Schmidt said the FIA's Charlie Whiting, surprised by the teams' new stance in Monaco, had asked team managers to draw up a list of their concerns.
That list was presented at a meeting in Montreal on Thursday, and will reportedly be tabled at the next Strategy Group, preceding a new vote.