A Qantas flight bound for the Philippines was forced to turn back to Sydney on Saturday after the pilot discovered a hydraulic fluid leak, just eight days after a major emergency involving another of the carrier's aircraft.

The Boeing 767-300 carrying 200 passengers from Sydney returned without incident, a Qantas spokeswoman said.

"There was no safety issue at any time," spokeswoman Melissa Thompson said.

Last Friday, a Qantas Boeing 747-400 flying from Hong Kong to Melbourne lost cabin pressure after a hole the size of a mini-van appeared in its fuselage following a blast believed to have been caused by an exploding oxygen canister.

The plane had to make an emergency descent from 29,000 feet to 10,000 feet before landing safely in Manila.