Oct.19 (GMM) Prodrive is unlikely to join the formula one action next year, Bernie Ecclestone admitted on Friday at the scene of the last grand prix of 2007.

David Richards' Banbury-based outfit is signed up to debut next March, but uncertainty about the touted 'customer car' rules and a legal challenge by Williams has probably compelled Prodrive to "give up", F1's chief executive told reporters at the Interlagos circuit in Brazil.

"I think they have decided to give up, haven't they?" Ecclestone, 76, said outside of Sao Paulo on Friday.

"They were all excited about coming in, it's a pity for them."

Prodrive, now nearly three months past its self-imposed deadline to organise other details including commercial and driver line-ups, has already admitted that its plans to run an identical McLaren-Mercedes package has fallen through.

Ecclestone said he thought off-the-shelf cars should "probably not" be allowed in F1.

"The teams say they are constructors spending for example about half a billion a year and the Prodrive budget was about 75 million," he noted.