A Qantas passenger plane had a safe landing at Sydney Airport after it encountered major engine problems shortly after it became airborne from Singapore.

The Boeing 747 encountered mechanical problems affecting one of the plane's engines.

One of the pilots discovered the mechanical failure in the Boeing 747 soon after the "near-full" plane left Sydney at 5.10pm AEDT. In a statement, Qantas stated that passengers in excess of 400 were on board, but were, by no means, in danger. They will have to wait on the jet till the engineers asses the aircraft, said Qantas.

Talking about the on-board passengers, a spokeswoman for Qantas said that they will be removed, only if the problem is major and the jet cannot be fixed quickly. In the latter case, an alternate flight will be arranged.

The Qantas spokeswoman said, "The pilot identified there was an issue with the aircraft and we believe it has impacted one of the engines. I can't speculate any further".

The Boeing jet, flying over sea when the issue arose, had to be turned back towards Sydney, dumping its fuel in order to meet requirements for its landing.