Aer Lingus has begun its Belfast International to Heathrow service claiming strong passenger numbers and sounding positive about the future for its €150 million hub - the first outside the Republic.

The first departure took off at 7:40am yesterday carrying the first of 700 Aer Lingus passengers booked on Heathrow services, chief executive Dermot Mannion said.

He forecast that the highest profile of the nine new routes out of the airport would be successful and would undercut the opposition.

Accompanied by John Doran, the airport's chief executive, Mr Mannion suggested Aer Lingus would expand its services further, but would not say to where. His remarks led Mr Doran to claim that passenger totals would pass the six million mark next year - up by more than 750,000 on current levels.

Aer Lingus was now the fourth largest carrier serving Heathrow, Mr Mannion claimed, coming in behind British Airways, Lufthansa and British Midland. He denied that current fares to Heathrow were lead-in prices which would eventually rise to competitors' levels.

In what was a relatively low-key launch of services to Heathrow, Mr Mannion admitted the switch of slots from Shannon to Belfast "had caused some difficulties", but he pointed to what he called the "continuing, very substantial base at Shannon" with transatlantic and European ser-vices. "We are committed to Shannon in the long-term," he insisted.

He declined to comment on the decision by property developer Liam Carroll to increase his stake in the company, saying only that he hoped to provide a return on all investments made in Aer Lingus.

Mr Doran contrasted the current position of Belfast International and the breadth of services offered to that which existed five years ago. "The number of services was quite small, basically just one international service. Today we have 50 services of which 36 are international."