The world's largest defence fair opened here on Tuesday, with a Chinese delegation among those surveying the wares on offer despite a European Union arms embargo against Beijing.

More than 40 countries are represented at the Defence Systems and Equipment International Exhibition, with about 1,300 exhibitors selling everything from machine guns, bullets and tanks to medical equipment and anti-bomb devices.

A Chinese delegation comprised of about nine members of the military and the Chinese ambassador are among those attending the four-day event, at the invitation of Britain's trade body, UK Trade and Investment.

But they will not be meeting any of the major defence contractors, UKTI spokesman Adam Thomas said, focusing instead on humanitarian and disaster relief equipment, as well as security technology including biometric devices.

China is subject to a Europe-wide arms embargo, which in Britain prevents the export of lethal weapons, their components or ammunition, military aircraft or platforms and any equipment that could be used for internal repression.

It was imposed by the European Union following the Tiananmen Square massacre in 1989.

This is not the first time a Chinese delegation has attended the DSEi show. They were here two years ago, and were also invited to the Farnborough Air Show, although they did not attend, Thomas said.

However, the Campaign Against the Arms Trade said they were "shocked" at the inclusion of China and rejected the argument that the delegations were only in London to see humanitarian equipment as an "excuse".

"We are shocked but not surprised," said media coordinator Kaye Stearman.

"China is such a massive abuser of human rights and there has been an embargo in place for more then 20 years. But then we do see components sold to China -- the rules are pretty flexible."

The defence industry in Britain accounts for more than 300,000 jobs and supplies 10 percent of manufacturing jobs here. Last year, it had a turnover of about 35 billion pounds, with exports worth a further five billion pounds.

Fifty-three major defence contractors are at DSEi this year to present their latest developments, including high-tech clothing for soldiers in combat and ways of delivering breathable atmospheres in nuclear-powered submarines.

British defence giant BAE Systems unveiled a new system to help commercial vessels fend off pirates, including an improved radar system and a laser to dazzle and temporarily disable potential attackers.

The technical wares on offer stretched from bullets to three full-scale naval vessels -- two from Britain's Royal Navy and one from the Dutch Navy -- berthed on the waterway outside the ExCel centre in London's Docklands area.

The Campaign Against the Arms Trade organised a small demonstration outside the UKTI offices in central London in protest at what Stearman called Britain's "cosy relationship" with the international arms trade.

Such is the security at the DSEi venue that protesters cannot demonstrate anywhere nearby.