Hundreds of people are being warned to watch out for measles symptoms after it was revealed a passenger on board a flight into Sydney Airport had the highly contagious disease.

The man flew from Manila aboard QF20 which landed in Australia on Friday morning about 6.30am.

He then visited a medical centre in Leichhardt where isolation measures were put in place.

NSW Health on Monday said those on the Qantas flight and at the airport on Friday morning should be alert until late January for symptoms such as fever, sore eyes and a cough.