Air travellers have been warned to expect delays next month when tough security measures come into effect limiting the amount of liquids that can be carried on board. The Civil Aviation Department said all liquids, gels and aerosols in cabin baggage would have to be carried in containers with a capacity not greater than 100 millilitres. All containers have to be placed in one transparent re-sealable plastic bag of a maximum capacity not exceeding 1 litre. The bag will have to be presented separately from other luggage for examination at screening points. Exemptions will be made for medication, baby milk and food, and special dietary requirements subject to verification. Travellers will still be able to make duty-free purchases. The measures, which take effect on March 21, will comply with guidelines issued by the International Civil Aviation Organisation (ICAO) in December after a failed terrorist plot to smuggle liquid explosives onto aircraft in England. Simon Li Tin-chui, chief operations officer of the department, said they decided to enforce the regulations from next month after considering the time needed to arrange the safety measures. 'We had to inform all concerned parties such as airline operators and security service providers.' The deputy chairman of the Legislative Council's security panel, James To Kun-sun, said the measures were not introduced immediately after the security scare last year because Hong Kong was not directly facing a threat. 'It seems the measures are being introduced simply because Hong Kong is an aviation hub where many flights to and from the UK and US - high-risk countries - make stops,' he said. Mr Li said: 'The regulation will be applied to both transit and departing passengers. We do expect there will be some delays, especially in the initial period of implementation. Passengers who refuse to dispose [of] restricted articles when requested [to] will be refused entry to the restricted area.' Passengers are advised to pack their liquid products in a plastic bag before going to Chek Lap Kok and to arrive at the airport three hours before departure time. Frequent flyer Ben Chuk said he did not mind the new measures. 'I usually put all those little bottles in one bag when I travel so I do not think it will cause a lot of trouble.' But his friend, Alice Chow, said it would be inconvenient for women who liked carrying facial creams.