They had been invited to meet FIA President Max Mosley in Paris later this month to discuss technical regulations for 2008 and their decision to stay away can be seen as further evidence that they are serious about the planned break away.
Currently only Ferrari is plans to be inside the F1 tent after the current agreement runs out in 2007.
"No one is going to attend the meeting with Max (on April 15), and there will be a press release to say that," BAR chief executive Nick Fry told Autosport-Atlas, reports Reuters.
"We have a great alignment between the nine teams and the five manufacturers...with each of the teams reporting positive progress and a good endorsement of what is going to happen.
"But this work will take a couple of months to complete. We are still heading towards our schedule of having something which we will be pleased to share with the FIA and (Formula One supremo) Bernie Ecclestone probably around July-August time."
The manufacturers alliance of BMW, Renault, DaimlerChrysler, Honda and Toyota want most of the revenues, a level playing field and far greater transparency.
