WASHINGTON — Poor decisions by airlines worsened a string of severe flight delays this year that left thousands of people stranded on tarmacs for up to 10 hours and carriers should be forced to set time limits for keeping passengers aboard delayed flights, a government watchdog reported yesterday.

A tough report from the Transportation Department's inspector general said airlines and airports still aren't well-prepared for dealing with stranded flights.

The report also called on federal aviation regulators to require better reporting of delays on the tarmac.

Lengthy delays on American Airlines flights in December and JetBlue planes in February triggered widespread anger among passengers.

"We found that neither airline had a system-wide policy or procedure in place to mitigate long, on-board delays and off-load passengers within a certain period of time," the report said.

Inspector General Calvin Scovel said there had been "little improvement" from what his office found in a similar review in 2001.

The report sided with American Airlines on one issue: It found that passengers' claims that they did not have adequate food, water and toilet facilities on some delayed flights were untrue.

Airlines generally oppose a strict time limit that requires pilots to return to the gate during a ground delay.