Knives will no longer be allowed on some flights departing Hong Kong, under new airline safety guidelines. The move by the Airport Authority comes after the US Federal Aviation Authority imposed strict new regulations, banning knives on US carriers and all US-bound flights in the wake of the terror attacks. Knives also have been banned by all UK carriers. Although the new guidelines affect only some flights from Chek Lap Kok, it is expected they eventually will apply to all flights from Hong Kong. But travellers will still be able to buy knives at Chek Lap Kok, despite the fact that the US hijackers used blades. Up until now the United Nations International Civil Aviation Organisation has limited blade length to 7.5cm for knives being taken on to planes. 'It would be prudent to assume that knives will not be allowed on to planes. Our advice would be to check it in your baggage but do not carry it in your hand luggage,' Airport Authority spokesman Chris Donnolley said. British Airways has said it will employ its own security measures. Mr Donnolley said Australian airports had banned metal cutlery on planes and at catering outlets on their premises. But Hong Kong travellers will still be able to buy knives at the airport from Victorinox, a Swiss firm selling knives. 'People can visit us before checking in and then make sure that they place the knives in their baggage. There is nothing harmful in this because it will be placed in the hold,' a spokesman for the firm said.