American Airlines' pilot union has indefinitely postponed the ratification vote for a tentative contract agreement, it said in a memo on Sunday.

The voting will now take place "at a date and time to be determined", the union said.

American Airlines pilots were due to vote on Monday after the company on Friday raised the value of its contract offer to pilots by more than $1 billion. The union had earlier warned that ratification was in jeopardy.

The Texas-based carrier said on Friday's changes brought the total value of the four-year proposed contract to $9 billion and would match the pay rates and retroactive pay in United Airlines' tentative agreement.

American Airlines did not immediately respond to a Reuters request for comment.

(Reporting by Rishabh Jaiswal in Bengaluru and Rajesh Kumar Singh; Editing by Nivedita Bhattacharjee)