Visitors have been surprised to see white smoke at the World Expo site - a park said to be emission-free.

It is, in fact, open-air barbecues - which have recently appeared at the Malaysia, Indonesia and Cambodia pavilions in Zone B - a sight common on back streets in Shanghai, but not strictly legal.

But what is more surprising is that these businesses have been organized by Expo officials to provide truly authentic foreign snacks for Expo visitors.

The snacks used to be served inside the pavilion using an electric oven. Some pavilion staff said the food only keeps its true flavour when barbecued with coal and not anthracite coal.

In front of the three pavilions, chefs were grilling chicken and fanning the flames. Smoke and sparks flew about every time the chefs turned the meat.

Some visitors held their noses and passed by quickly, but many others lined up to buy a tasty treat.

"It was a choice for the organizers between the typical and authentic tastes and a bit of air pollution," said Lu Yi, an official of the Managing Department of Zone A-B at the site.

Grilled marinated chicken served in various sauces, also known as Satay, is available almost anywhere in °?Indonesia, is the national dish of the country and is highly popular worldwide.

The organizers agreed to let the pavilions use barbecues after a visiting Indonesian government minister complained that the taste of meat from electric ovens was not authentic and asked the organizers to allow the pavilion to use a real barbecue.

It was the organizers who asked them to move the barbecue outside to avoid the risk of fire, Lu added.

Lu said food safety officials inspected all the raw materials and firefighters were standing by to ensure safety.

"It was hard for the organizers to reject the request because the pavilions said the food is part of their cultures and should be showcased at the Expo," Lu said.

Zhou Lixin, manager of the Indonesia Pavilion restaurant Enak - "delicious" in Indonesian - said barbecued chicken kebab was one of the most popular dishes in the restaurant. Four skewers of kebab cost 28 yuan (US$4.20).

On average, more than 4,000 kebabs were sold every day - far above the expectations of the Indonesia pavilion before the Expo opened, Zhou said.