The countdown to the launch of the futuristic building came as construction workers finished the first phase on time.

The metal structure of Skyhub now dominates the former site of the walkway between the main terminal and T2.

It will house the most advanced security zone in the UK when it opens in October, and it represents the biggest single investment at the airport since the international pier opened in 1994.

All passengers will be channelled through the two-storey hub, which will have bars, shops and restaurants.

Gordon Dewar, the airport's managing director, joined staff from contractors Balfour Beatty at a special ceremony to mark the completion of the main structure.

He said: "We are delighted with the progress being made.

"With Skyhub, everything will be under one roof.

"No matter where you're travelling, once you've passed through security, you can eat, shop or relax any- where in the terminal."

The 4000sq ft security zone - the size of a football pitch - will be bathed in natural light as the entire front of the building will be covered in translucent cladding.

The revolutionary system, called Kalwall, has been used at Orlando Sanford Airport in Florida, Arsenal's Emirates Stadium and Nasa's base at Cape Canaveral.

The material is energy- efficient, allows daylight to flood into the building and retains heat.

Skyhub is part of a planned £200m, 10-year investment at Glasgow Airport by operator BAA Scotland.

Tim Clarke, divisional managing director for Balfour Beatty, said: "Working in a live airport environment produces its own challenges.

"This calls for the highest calibre of people working together with the client, design team and supply chain."

Councillor Iain Nicolson, Renfrewshire's depute Provost, who attended the ceremony, said: "Glasgow Airport is going from strength to strength and this investment will significantly improve the customer experience.

"The Skyhub will mark the latest phase of BAA's programme to build on that success."