A major gas leak at Heathrow Airport forced hundreds of guests out of a hotel and caused dozens of flights to be cancelled or diverted last week.

Emergency services were called in after a digger at a construction site beside Terminal 4 ruptured a gas main at about 12.30pm, sending methane gas into the air just below the flight path to the airport's southern runway.

A 200metre exclusion zone was set up, disrupting air and road traffic.

BAA, which runs Heathrow, was forced to cancel and divert 37 incoming flights during the disruption that lasted for several hours. Heathrow police closed the A30 causing major traffic delays.

Mark Phillips, station manager at Feltham Fire station, said: "It was such a large gas main leak that we had reports of the smell of gas from people living two miles away.

"The danger was if the air had come into contact with any ignition it would have flicked and gone up."

The National Grid advised more than 300 guests and staff at Jurys Inn Heathrow hotel to evacuate just before lunch time.

The guests, many who had flights to catch or luggage still in their rooms, were not let back in until 11.30pm.

A spokesman from the gas and electricity supplier said a JCB digger ruptured a medium pressure gas main at the construction site, which was next to the Jurys Inn.

Fire crews in breathing apparatus used a machine to dampen the escaping gas with fine spray of water to keep it from wafting over Feltham and Hounslow.

More than 20 firefighters from Hounslow worked on the emergency for five hours.