Scanners capable of detecting liquid explosives will be installed in all of China's 147 airports before the 2008 Olympic Games, a top official said.

"All civil airports will be required to install at least one such scanner starting from next year," said Yang Chengfeng, head of the public security division under the General Administration of Civil Aviation (CAAC).

Yang said CAAC had been looking for effective methods to detect liquid explosives, since British police said in August they had foiled a plot to blow up aircraft with such explosives.

"Liquid explosives have become a big threat to aviation security globally," he said.

The new scanners, made by Beijing-based NUCTECH, can detect liquid explosives in only five seconds.

The current method of detection that Chinese airports adopt smelling or asking the traveller to take a sip of the liquid takes a much longer time.

"Using the new scanners at airports can reduce passengers' waiting time," Yang said at a news conference on Tuesday in Beijing.

But he stressed that the present ban on liquids would still be in effect after the scanners are put into use.

China now bans almost all liquids and gels aboard an aircraft, except food for travelling babies and medicines if the prescription is in the ticket holder's name.

According to Yang, the scanners will be in place before the 2008 Beijing Olympic Games.

"We have confidence the Olympics Games will be safe," Yang said.

CAAC will adopt special security measures to ensure safe and convenient travel of passengers. Athletes will pass through separate security channels.

The China-Africa Summit proved to be a successful rehearsal for the Olympics, when 48 state leaders came through the Beijing Capital International Airport.

CAAC has required all liquids to be checked following a crash on May 7, 2002, off the northern city of Dalian, which killed 112 people. The accident was blamed on a passenger setting fire to gasoline carried in soft drink cans.