British Airways is to axe its "red-eye" early morning flights from Glasgow to Heathrow.

The flag-carrier yesterday said the service would be dropped on October 27, sparking renewed concerns among business leaders about its commitment to Scotland.

BA has come under fire from trade unions for what they see as its gradual pull-out from Scotland - it focuses on feeder services from Glasgow, Edinburgh and Aberdeen to London airports.

But even after the latest cut, the airline will run around 100 flights a day between Scottish airports to the UK capital and experts stress the importance of its shuttles for Scotland's connectivity.

One senior industry source yesterday said: "Airlines are always looking for the most lucrative routes for their aircraft. We take BA's flights to Heathrow for granted at our peril. Passengers should use them or lose them."

Some aviation commentators have warned that BA could drop Scottish flights to free up slots at Heathrow for more profitable long-haul services. The airline itself has dismissed these claims.

"Our Scottish passengers and the Scottish operation are extremely important to British Airways," a spokesman said. "This is more than adequately demonstrated by the fact that we operate more flights a day to and from Scotland than we do to any other part of our world-wide network."

BA's earliest flight out of Glasgow will now be at 7.05am rather than 6am. Business travellers will struggle to get to London for a 9am meeting. The first service will be carried out by a larger plane, an Airbus A321, to make up for some of the drop in capacity. Overall, the number of flights from Glasgow to Heathrow will fall from 10 to nine.

Business leaders expressed their concern at the cuts.

Richard Cairns, chief executive of Glasgow Chamber of Commerce, said: "We would expect BA to base its schedules on levels of demand, but it is also important that it takes account of the need for flexibility of early morning travel for business users."

BA will have five return flights a day to Gatwick (the first at 6.15am) and four returns to London City.

"We continually amend our schedule to take account of business requirements and in the interests of our operation as a whole," the airline's spokesman said.

"Even with the change to the Glasgow-Heathrow schedule, we will continue to operate more services to Heathrow from Glasgow - and Scotland as a whole - serving Glasgow, Edinburgh and Aberdeen, than any other airline.

"On Glasgow-Heathrow alone, we will provide more than 1200 seats a day each way, connecting Scottish business and leisure passengers with London and onto our extensive European and worldwide network."

Willie Walsh, BA's chief executive, spoke of the importance of transfer passengers to Heathrow. He was responding to criticism from David Cameron, the Tory leader, and Bob Ayling, one of his predecessors at the airline, that passengers from Scotland interlinking through Heathrow did little good for the UK economy.

Mr Walsh said: "This suggestion is extremely insulting to the millions of UK residents who regularly fly to Heathrow to catch connections to distant parts of the globe ."