Passengers had to be led to safety today after a British Airways Boeing 777 flying in from China reportedly landed short of the runway at the UK's biggest airport.

Witnesses said around six fire engines were at the scene of the incident. The aircraft's emergency chutes were deployed and the aircraft was doused with foam.

A Heathrow airport spokesman said: "A British Airways flight arriving from Beijing carried out an emergency landing at 12.42pm. Passengers have been evacuated and there are currently no reported injuries.

"The Heathrow southern runway has been closed, but the northern runway remains open.'' The incident happened as Prime Minister Gordon Brown was due to leave Heathrow for China and India. His flight was delayed because of the incident, but his jet was not involved directly.