"I'd rather have 10," the F1 chief executive told Reuters on Thursday. "I never wanted 12."
HRT's departure leaves just 11 teams on the grid for 2013. It emerged recently that the struggling backmarker Marussia is the only team on the 2013 entry list that is yet to be offered a new Concorde Agreement deal.
"It's just that 10 is easier to handle, for the promoters, for transport," Ecclestone said.
He thinks it is unlikely anyone will step up to rescue HRT, who according to one unpaid supplier is already in liquidation.
"I wouldn't think that anyone would want to (save HRT)," said Ecclestone.