Threatening note found on Qantas plane. Picture: Mark Stewart

Emergency services are at Queenstown Airport, in the country’s South Island, after a threatening note was found on a plane.

It is believed the note alluded to a bomb and was found on a Qantas plane by a cleaner.

There were no passengers on board at the time but the plane will remain grounded while police investigate.

It’s believed the plane flew into Queenstown from Australia and the note was found just before 3pm (1pm AEST).

According to stuff.co.nz, the note was found on the QF121 flight from Sydney.

Fraser Mackenzie, who was picking up somebody from the airport, told the news site those who hadn’t been through customs were evacuated to the runway side of the airport.

The airport has since reopened and it is running as normal but major delays are now expected.

Police did not find any explosives while searching the plane, airport terminal and baggage.

Earlier the NZ Herald was told passengers were moved 50 metres from the terminal and about 100 metres from the plane.

A person preparing to fly to Christchurch told NZ Herald there were fire trucks on the tarmac.

“The mood is muted. Some people are quite worried but people just want to get out of the cold,” the passenger said.

Virgin and Jetstar flights were still taking off despite the note.

Qantas is not issuing a statement about the incident and said the airline would leave it to New Zealand police to investigate further.