Three new cases of measles have been diagnosed in Melbourne with authorities fearing more people may have been exposed at several locations across the city, including a popular Greek restaurant, Melbourne Airport and a CBD-bound tram.

A woman in her fifties is being treated in hospital, while a man and a woman in their thirties are being treated at their homes.

The three adults are being treated after catching measles. Credit:Nine

Chief Health Officer Brett Sutton has warned punters who visited the Futsal Oz stadium in Thomastown in the city's north, people who dined at the Hellenic Republic restaurant in Brighton and travellers who passed through Terminal 3 at Melbourne Airport towards the end of last month they may be at risk.

Authorities also warned commuters who travelled on the 109 tram route from Port Melbourne to the CBD between December 3 and 5 to keep an eye out for symptoms.