Melbourne taxi drivers have blockaded the Melbourne Airport's main forecourt to protest the lifted ban on UberX pick-ups.

Disgruntled taxi drivers have blocked roads leading to the airport and stopped picking up passengers about 9.30pm on Tuesday night, leaving travellers to take buses into the city.

The protest comes just 12 hours before UberX is scheduled to begin operating at the airport.

Angry passengers took to social media to vent their frustration at the delays, with one commuter claiming he caught a taxi, whose driver demanded the fare upfront, only to be dropped on the roadside one kilometre from the airport.