Passengers hoping to get on their morning flight out of Melbourne Airport on time have been met with delays, after a fire alarm went off in the control tower.

According to radio station 3AW, air traffic controllers were evacuated so all inbound flights had to be suspended.

This left some aircraft circling about the airport awaiting instruction.

Melbourne Airport confirmed the tower had to be evacuated due to an alarm, but all flights were now operational.

The spokesman told news.com.au there may still be slight delays due to the domino effect from the shutdown, but passengers should travel to the airport as normal.

At the time of the shutdown, no planes were allowed to land, forcing inbound flights to circle the airport.

It is understood that four flights were diverted to Canberra and another two to Sydney during the time when the control tower was not available.