Authorities have been unable to find a Vietnamese man who escaped from Serco guards at the Perth International Airport as he was being deported.

A spokesman for the Immigration Minister says the man fled while under escort at the departures check-in area on Saturday morning.

Australian Federal Police officers who were at the airport helped WA Police and Serco staff search for the man, but they were unable to locate him.

The spokesman says the man travelled to Australia by boat illegally.