Cameron asked to block Circuit of Wales state aid
24 March 2014 Last updated at 14:10 GMT
Silverstone racetrack bosses have asked David Cameron to prevent tens of millions of pounds of potentially "illegal" state aid being used for a new £280m circuit in Wales.
Developers behind the Circuit of Wales scheme in Ebbw Vale, Blaenau Gwent, are said to be asking the Welsh and UK governments to commit up to £50m.
Silverstone's MD has written to the prime minister to intervene.
Planning issues have delayed the start of work at the site.
BBC Wales business correspondent Brian Meechan explains.