A SUSPECT bag has caused a security alert at Heathrow airport's terminal four.Thousands of passengers are now facing delays.The terminal has now been evacuated and all roads leading to it have been closed.

A SUSPECT bag has caused a security alert at Heathrow airport's terminal four.

Thousands of passengers are now facing delays.

The terminal has now been evacuated and all roads leading to it have been closed.

The alert comes amid heightened security following failed terrorist attacks in London and Glasgow.

A spokesperson for the airport said: “As an extra precaution, it was decided to perform secondary searches on all departing passengers at the aircraft gate.

“In order to facilitate the secondary search process, a decision was made by the police to partially evacuate the departure lounge and re-screen the passengers.

“Contingency plans have now been activated to ensure that we are able to effectively manage the increase in resource that this secondary search requires.”

Terminal 4 is used by KLM, British Airways, Qantas Airways and Sri Lankan Air.