Hamburg Airport is on lockdown after the entire building was evacuated as pepper spray leaked into the air conditioning system.

German officials said 68 people were coughing, suffering breathing problems and burning eyes after the incident and nine were taken to hospital.

It is thought a canister of the substance used to control riots was set off in a bin near the security check-in desks.

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Firefighters take care of a casualty on a stretcher inside the terminal building in the airport

Travellers wait outside Hamburg Airport in northern Germany, after the chemical leak

Firefighters with multiple vehicles stand in front of Hamburg airport as passengers leave the terminal on February 12

Passengers are made to wait opposite the terminal building as emergency services arrive

Specialist fire crew arrive at terminal two, which has been cordoned off with sheeting

Hundreds gather outside the airport as emergency services move in to deal with the leak

Dozens of emergency vehicles line the road outside the terminal at Berlin Airport

A man talks on his phone while pushing his luggage as emergency services staff direct people

Huge crowds gathered outside the terminal building having been evacuate from the airport

The alarm was raised when what is describes as a 'nasty odour' swirled around the airport.

All flights were grounded until the issue was resolved.

Passengers and flight crew were sent to the car park away from the terminal in temperatures as cold as -4 degrees Celsius, according to local press.

Flights were halted at 12.20pm due to the fire brigade taking over the terminal building.

A total of 13 flights were said to have been affected by the disruption, and two of them had to be diverted more than 100km away to Bremen.

Other planes were either left circling or on the runway.

Firefighters and ambulances were rushed to the scene after the incident, which occurred in an area where passenger luggage is scanned by security staff.

Lightly dressed passengers were rushed outside the terminal but were allowed back in shortly after, the police spokeswoman said.

A spokeswoman for the airport said flights had resumed as of 1.45pm local time.

The incident bears a striking resemblance to a situation that closed City Airport in London back in October.

Then, more than two dozen people were treated for breathing difficulties in a suspected chemical incident that sparked an evacuation.

After a three-hour investigation by police and firefighters in protective clothing, it was declared that pepper spray discarded by a passenger was the cause.

David Morris, 28, said he was checking in for a flight to Edinburgh when he started coughing.

'It was getting quite bad and we saw other people starting to cough at the same time,' he said.

'The people behind the desk were coughing the most and quite aggressively.

'Within two minutes, they shouted for everyone to get out,' Morris said.

The London Ambulance Service said four ambulance crews and its hazardous area response team were sent to the scene. It said crews treated 27 patients at the airport for 'minor breathing difficulties.'

Two of them were taken to hospitals.