SYDNEY (AFP) - A Los Angeles-bound United Airlines jet had to turn back to Sydney on Sunday after experiencing a problem on take-off, with reports that it had suffered a tyre blowout.

The Boeing 747 had to circle the Australian city several times to dump fuel before making an unscheduled landing not long after takeoff at 3pm (12 noon Singapore time).

A Sydney Airport spokeswoman said Flight UA840 "has returned to Sydney Airport following a problem experienced during take-off.

"The aircraft has landed safely and passengers and crew are currently in the process of returning to the terminal," she said.

The Australian Broadcasting Corporation said the jet blew one of its tyres on takeoff, though that could not be confirmed by transport officials or the airport.