New York, Apr 17 (IANS/EFE): American Airlines, the No. 3 US carrier, Tuesday grounded all its domestic flights due to a problem that paralyzed its electronic reservation system.

In a message via Twitter, American Airlines announced that none of its aircraft flying domestic routes would be taking off until 5 p.m. while problems with the system were resolved.

The airline had announced around midday that the tool it uses for its reservations network, Sabre, had gone down, but shortly thereafter it said that the problems that were preventing access to its system were not related to Sabre.

"We are working to resolve this issue as quickly as we can, and we apologize to our customers for this inconvenience," AA spokeswoman Andrea Huguely said on Twitter.

American Airlines, which operates more than 3,500 daily flights worldwide, entered bankruptcy reorganization in November 2011 and in February it announced an $11 billion agreement to merge with US Airways and create the world's largest airline.