HONGKONG Bank and Citibank have taken the battle for dominance of the credit card market to the skies, by linking spending on their cards to airline frequent flier programmes. Another major player, American Express, is believed to be close to announcing a similar deal. Hongkong Bank has teamed up with United Airlines, giving holders of the bank's Visa, Mastercard and JCB Gold Cards a kilometre of free flight on the airline for every eight dollars they spend. The deal will be available from September 1 to all card holders in Hong Kong, and will soon be expanded to other Asian countries. ''This is a world first,'' said Mr David Solloway, United Airlines general manager in Hong Kong. ''It is the only partnership between an airline and a banking group which involves all their credit cards, not just affinity or private label cards.'' But Citibank yesterday launched a similar scheme - called Preferred Passages and involving Cathay Pacific, Singapore Airlines and Malaysia Airlines - which it also claimed as a world first. Citibank Gold Card holders who enroll in the programme will accumulate free kilometre credits if they charge their cards. ''We were originally going to join the Passages deal, but there were a couple of minor points we insisted on and they could not be agreed so the deal fell through,'' said Hongkong Bank's card products division senior manager Richard Cromwell. United was the only airline in the Hongkong Bank scheme, but others were in negotiation, Mr Cromwell said. In the Hongkong Bank programme, even purchases on charge cards designed for use in specific shops, such as Joyce or Lane Crawford, will count for kilometres. Unlike the Citibank scheme, Hongkong Bank's deal with United covers economy flights. The banks involved in the promotions are watching each other's moves closely. Even the timing of the announcements of their respective airline links is being treated as strategically important. Citibank offered news of its joining Passages earlier this week, on condition that it wasn't released until today, while American Express arranged, then cancelled, press conferences for both yesterday and Wednesday, the same day public relations firm Ogilvy & Mather announced the bank had joined the Passages scheme.