A major safety investigation is under way after an aircraft is believed to have flown over Clacton into Heathrow Airport with a dangerously low level of fuel.

The flight path of the Far East-operated 747 took it over the town before continuing on to London.

The aircraft is believed to have had just four tonnes of fuel on board which is significantly below the minimum capacity required by law.

A spokeswoman for the Civil Aviation Authority - which is responsible for aircraft safety - confirmed the incident was being investigated.

She said because the CAA was only responsible for British airlines, the matter had been reported to the Department of Transport.

It had asked the body which regulates foreign operators to investigate and make a full report.

Under British rules, an aircraft has to have enough fuel to land, make one circuit of the airport and to land at an alternative airport or hold its position in the air for up to 30 minutes before landing.

The aircraft under investigation had made a 14-hour journey before coming in over Clacton. Four tonnes of fuel is a fraction of the planes' capacity of 208 tonnes.

A Department of Transport spokeswoman said today: "The incident has been taken up urgently with the Government of the airline concerned and the airline itself.

"If we consider any airline to operate unsafely, we will consider withdrawing permission for them to enter Britain."

Roger Stewart, assistant chief executive of Tendring Council, said the council was well aware of the high number of aircraft movements across the district because it was an international air corridor in and out of the UK.

"The potential implications of various types of air incidents are regularly discussed with other emergency planning agencies," he said.

Harwich MP Ivan Henderson has written to Transport Minister Glenda Jackson asking for information.

"Aircraft safety standards in our country are extremely high but when an incident such as this occurs over my constituency I obviously am concerned," he added.

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