Singapore Airlines flight from Melbourne cancelled after pilot 'fails alcohol test'

An international flight from Melbourne has had to be cancelled at the last minute after the pilot allegedly failed a random alcohol test.

The Singapore Airlines flight was due to depart Melbourne for Wellington on Saturday when the pilot failed a random Civil Aviation Safety Authority blood alcohol test.

"The pilot in question did not pass the test due to having a higher than suitable blood alcohol limit," Singapore Airlines said in a statement.

"The pilot in question was stood down and has been suspended from all duties effective immediately.

"He has returned to Singapore where a full investigation will be undertaken."

The return flight from Wellington was also cancelled.

The flight was meant to be flown on the Boeing 777 aircraft, with the capacity to seat more than 270 people.  

Singapore Airlines has "sincerely" apologised to all passengers who were left stranded.