Membership is based on the number of kilometres a passenger flies in a given time period, and there are three different levels: green, gold and diamond.

A passenger must fly 40,000 km in six months for green membership, 80,000 km in a year for gold and 250,000 km in a year for diamond.

The benefits range from an exclusive travellers' hotline and priority check-in by phone or fax, to luxurious lounges to which gold and diamond cardholders can invite guests, and advanced seat reservations for groups of up to five.

A Cathay Pacific spokesman said: ''As a Marco Polo Club member, you can book more easily, check in more conveniently and fly more comfortably.'' Membership of the Marco Polo Club also qualifies you automatically for the Passages frequent-flyer programme, which offers free flights on the accumulation of certain mileage limits.

British Airways describes its offerings as ''stepping into a new world''.

Its Club World has a fast-track channel at London's Heathrow and Gatwick airports which reduces time spent on security formalities, and new arrivals' facilities where the member can take a shower and have breakfast. In addition, first class offers a new lounge and priority transfers between terminals at Heathrow.

A British Airways spokesman said: ''If you fly regularly on business, you should join the British Airways Executive Club.'' Qantas, in its turn, emphasises its distinctly personal service, its lounge facilities, and shower facilities in its Captain's Club scheme. There are also facilities for conducting business, priority wait-listing for flights, and discounted hotel and carrental rates.

Its spokesman said: ''Qantas is a specialist in understanding comfort and service.'' In addition, the airline offers a priority disembarkation and an entertainments service which passengers can use to book tickets for shows.