The measure was expected to provoke complaints from Taiwanese vegetarian passengers already riled by the limited choice of in-flight food, the Chinese-language Liberty Times daily reported Monday.

China Airlines, Mandarin Airlines, EVA Airways, Uni Air and TransAsia Airways said they would adapt their vegetarian offerings and supply more uncooked vegetable choices.

The change in the regulations is the result of following Indian vegetarian rules and a lack of understanding of practices prevalent with vegetarians in East Asia, reports said.

Vegetarians in India are not allowed to eat vegetables that grow under the soil and never see the light of day, reports said. IATA may not understand the eating habits of Asian vegetarians from outside India, said Liu Tsan-hsiung, top cook at EVA. He said his airline would first gauge passenger reaction before considering filing an application with IATA to change the rules.

Meals on Taiwanese airlines will no longer be able to use local favorites like sweet potatoes, carrots, potatoes and even ginger, Liu said. Without ginger, it will be difficult to achieve the traditional Taiwanese flavors, the Liberty Times quoted the catering official as saying.

For 50 years each airline in the world decided on its own what kinds of menu it could offer, but now for the first time, IATA drew up 54 types of menu tailored to a variety of passengers from vegetarians to children and infants to members of religious groups. IATA was not only listing the menus, but also regulating the ingredients that could be used.

While expected to result in complaints from some passengers, the new food rules mean that travelers will no longer accidentally eat food that might violate some of their own rules or religious guidelines.

The key problem is that rules for vegetarians vary from culture to culture. Some vegetarians do not eat dairy products, Taiwanese reject onions and garlic, and followers of some yoga schools are not allowed to eat mushrooms. Because of the different sets of bans, many vegetarian passengers complain about the extremely limited list of suitable in-flight meal choices. Often the final choice is eating a raw vegetable salad, the Liberty Times reported.

Caterers say vegetarian food is a growing market for airline meals. An estimated 33 percent of Taiwanese citizens regularly come in touch with vegetarian cuisine, and 10 percent of Taiwanese airline passengers will order specially tailored meals, with Asian-style vegetarian meals the vast majority.

Two major air catering companies, linked to the Grand Hotel and TransAsia, say they prepare 60 types of vegetarian meals a day, with orders coming from passengers on just about every flight.

Catering officials say passengers should be more vocal about their vegetarian preferences and especially about the absence of suitable dishes. Vegetarian passengers often have the feeling that they receive different treatment despite paying the same fare as other travelers.

The caterers say they usually do not include dairy products in their vegetarian meals, unless airlines specifically request it.

Many Asian airlines receive positive marks for balanced vegetarian meals, but Japanese companies are criticized for the small quantities, while on flights to China, the only choice is often eating one biscuit, one cake, and drinking one cup of tea, according to reports.