Ecclestone is referring to commercial arrangements that have already been made with the sport's existing supplier.
But there is no such contract between Pirelli and F1's governing FIA beyond 2013.
That has ramped up the pressure on the already-frustrated Italian company, who said moves to change F1's supplier now would be "farcical".
"If Michelin wanted to return why didn't they come out and say so last September?" motor sport boss Paul Hembery told the Telegraph.
He was speaking at Spa-Francorchamps, where after Friday's punctures for Sebastian Vettel and Fernando Alonso, he had to show photographs to journalists to prove the problems had been simply caused by debris.
"We can't even get a flat tyre now?" Hembery is quoted by Autosprint.