The FIA is to open the tender process for a standard engine in Formula One from 2010, in a move that could drive manufacturers away from the sport.
Mosley wrote to teams last week telling them that he was considering introducing standard engines as a way of driving down costs. It comes ahead of a team principals' meeting in Geneva next week to discuss urgent cost cuts.
It was widely believed that Mosley's threat was simply a way of forcing through other changes, because of the hugely controversial nature of stipulating manufacturers run a standard engine.
However, in a shock statement issued in Shanghai on Friday afternoon, the FIA announced that it was to open the tender for a standard supply of engines - suggesting the plan was going ahead.
The statement read: "The FIA will today open the tender process for the appointment of a third party supplier of engines and transmission systems to be used by competitors in the 2010, 2011 and 2012 FIA Formula One World Championship.
"The tender summary and requirements will be published on the FIA website shortly."
Manufacturers made it clear in Japan last week that they were against the move to a standard engine - and some suggested that they would withdraw from the sport if they were introduced.
McLaren F1 CEO Martin Whitmarsh said about the effect of a standard engine: "It does have a pretty big impact on Formula One - I imagine it would lead to quite a few of the engine manufacturers leaving the sport."