Officials in the northern Italian city of Bologna have closed down the local airport as fire officials, trained to handle biological and chemical threats, swept through a plane parked on the tarmac.
A dispatcher with the local fire department said on Thursday the foreign plane did not have passengers on board.
However, its crew had to be evacuated before the aircraft could be searched, the dispatcher said.
No other details were immediately available.
The scare at the airport happened shortly before 5pm on Thursday, about four hours after explosions struck three London Underground stations and a bus, in a less deadly replay of the bombings that killed 56 people two weeks ago.
Bologna is 105km north of Florence.