A spokeswoman for the airport said the extra security was in line with measures being put in elsewhere in the country.

She would not talk about the details of the increased security but said it was not a reaction to a specific threat.

The airport's operations were not being affected by alert which began on Thursday morning.

'Not beaten'

The north terminal at Gatwick Airport was closed and a man arrested on Thursday afternoon after the discovery of a live hand grenade.

Two men were also arrested at Heathrow Airport in the morning as a "precautionary measure".

Travellers at East Midlands Airport would not notice a changed in their plans, said the spokeswoman.

"We can confirm in line with other UK airports that security has been enhanced.

"However, this is a precautionary measure and no way a reaction to any specific threat."

She said she could not comment on the details of the increased security but added: "A very important point in the current climate is we are not going to be beaten."