UPDATE 1-Motor racing-Angry Mosley calls F1 deal into question

* Mosley demands apology from Montezemolo

* FIA president says keeping options open

* Ferrari have no comment

(Adds detail, Ferrari reaction)

By Alan Baldwin

LONDON, June 25 (Reuters) - Motor racing chief Max Mosley called into question a deal securing Formula One's future on Thursday in a letter demanding a public apology from Ferrari president Luca di Montezemolo.

In the document, seen by Reuters, the International Automobile Federation (FIA) president suggested that he could rethink his decision to stand down in October.

Mosley said he and Montezemolo had agreed a deal at a breakthrough meeting in Paris on Wednesday to "present a positive and truthful account to the media" of what had happened.

That meeting ended the threat of a breakaway championship led by Ferrari, with teams accepting more cost cuts and Mosley agreeing to step down.