The Department of Transport yesterday declined to make any comment pending an investigation into the chain of events that resulted in a Departmental note, marked "for the Minister's information" on 13 June last, not being forwarded to Dempsey.

However, well-placed sources have told the Sunday Tribune that the inquiry is likely to find that the breakdown in communication happened because of an error whereby an email attachment sent between two Department of Transport officials was not opened.

Government sources insist Dempsey was not told the Shannon-London Heathrow service was in danger until late July, at which point he immediately arranged to meet Aer Lingus management.

Meanwhile, an attempt by Fianna Fail TD John Cregan to address yesterday's rally on the Shannon issue in Limerick City was drowned out by a chorus of boos. Thousands of people attended the rally which was addressed by local politicians and former rugby international Peter Clohessy.

It has also emerged that Bertie Ahern has written to the company responsible for applications for new slots at Heathrow expressing support for a bid by Astraeus Airlines, which is considering operating services between Heathrow and Shannon. A grey market for Heathrow slots takes place in Toronto next month and Astraeus is one of the airlines likely to bid.