A Lufthansa flight carrying 85 passengers was forced make an unscheduled stop after a strange smell entered the aircraft from the kitchen.

Cabin crew onboard the plane, which was travelling from Frankfurt to Madrid, had reported an ‘undefinable smell’ from the kitchen.

It was decided that the plane should be diverted so that the odour could be investigated.

The Airbus 320 touched down in Zurich at 8.25am local time (07:25 BST), according to an airport spokeswoman.

Lufthansa spokesman Peter Schneckenleitner said the move was ‘purely precautionary’, but according to reports three members of the cabin staff were taken to hospital for observation after complaining of respiratory problems.