AIR traffic control bosses were fending off claims today that the Swanwick centre has been hit by more technical problems.

In the latest revelation an un-named air traffic controller claims that there have been several occasions when communications between pilots and controllers has cut out erratically.

According to the senior air traffic controller there have been several instances when the technical controller isn't able to hear transmissions from the aircraft or confirm that information has been received.

He said: "Potentially it's dangerous, of course, because he will assume instructions he's given are not being followed. Where decisions have to be made very quickly, this obviously can cause some confusion."

But National Air Traffic Control bosses have strongly defended their safety record.

A spokesman said: "Safety is at the heart of the United Kingdom's air traffic control service.

"NATS would never do anything to compromise its safety standards. Neither would the Civil Aviation Authority, its independent safety regulator, permit it to do so. The air traffic control centre is very capable of safely meeting demands for the next 30 years."

The claim is the latest in a catalogue of problems for the multi-million-pound

centre that has been dogged with repeated criticisms of working practices and software problems.

Back in January it emerged that a design fault existed in the 350 computer terminals that meant air traffic controllers were unable to tell the difference between the numbers eight, six, and zero.

A leaked health and safety report also advised centre bosses that working conditions were unsatisfactory and could have implications for passenger safety.

In the latest revelation it is also claimed controllers are still not able to see the screens clearly.

The screens had green labels for planes the staff were working with, and white labels called "background tracks" for planes the operator was not talking to.

The controller said these background tracks were a "serious" problem, because they were not bright enough to be seen clearly.

Swanwick opened in January at the cost of £623m to replace a centre in West Drayton, near Heathrow and has already handled over one-and-a-half million flights.

Engineers and support staff based at Swanwick are now responsible for some 200,000 square miles of airspace above England and Wales.