Passengers can expect some minor delays to flights at Melbourne Airport after its air-traffic control tower was evacuated when a smoke alarm went off due to smoke from the bushfires.

Air-traffic controllers were evacuated from the tower at about 2.10pm on Tuesday as a precaution, which resulted in planes due to take off being held on the ground and aircraft in the air assuming a holding pattern.

Controllers were kept out of the tower for about 20 minutes.

Firefighters have since cleared them to return to the control tower, and full operations at the airport have resumed.

Airservices Australia, which manages the country’s civilian air space, said it believed smoke from bushfires may have triggered the alarm.

Just after 2.30pm Airservices Australia tweeted that staff had been given the all clear to return to the tower and that “normal ops will resume shortly”.

Melbourne Airport said the disruptions would be ‘‘quite minimal’’ partly because the evacuation of the control tower had occurred during an off-peak period.

‘‘The schedules are now back on track, so there aren’t a lot of flights affected,’’ a spokeswoman said.

with Beau Donelly