Prime Minister David Cameron leads a heavyweight group of British politicians and business chiefs on a visit to China this week which will focus squarely on expanding trade ties with the world's second largest economy.

Cameron leaves London on Monday for talks with Chinese Premier Wen Jiabao and President Hu Jintao as he stops in Beijing en route to the G20 summit in South Korea when China's role in the global economy will be centre stage.

Featuring more than 40 business leaders and four of Cameron's senior ministers, it is the biggest such delegation Britain has ever sent to China.

This is a vitally important trade mission. Our message is simple: Britain is now open for business, has a very business-friendly government, and wants to have a much, much stronger relationship with China, Cameron said.

I'm delighted we've got such a wide range of institutions and businesses coming with us. This visit will mark another step to making Britain the successful, open, trading and pro-business country that I want it to be.

Chancellor George Osborne and Business Secretary Vince Cable arrived in Beijing over the weekend.

The visit mirrors a trip to India earlier this year when Cameron courted business there and fits with the Conservative leader's pledge to give a greater commercial edge to diplomacy.

The British government has announced sharp spending cuts and businesses are looking to overseas demand to help fill their order books. Britain seeks to woo inward investment.

Diplomatic ties between Britain and China have become stronger since the British handed back Hong Kong in 1997 but previous trade missions to the world's most populous nation have brought relatively limited rewards.

Trade between Britain and China is increasing, totalling more than $35 billion (22 billion pounds) in the first nine months of the year, up by 30 percent on the previous year.

However, officials note that Britain still does more business with Ireland than it does with Brazil, Russia, India and China combined.

RIGHTS CRITICISM SEEN MUTED

Western nations are competing with each other to sell more to China's 1.3 billion people as part of efforts to rebalance the global economy.

Visiting France in recent days, President Hu oversaw the signing of $20 billion worth of corporate investment contracts and pledged to double China's annual trade with France to $80 billion over the next five years.

China is keen to learn from Britain's experience as it develops Shanghai into a global economic hub, and also looks to British banks to provide know-how as Chinese banks increasingly step out onto the global stage.

China will be hoping that Britain does not bring up in public thorny questions such as imprisoned Nobel Peace Prize winner Liu Xiaobo and other dissidents like Gao Zhisheng, as well as avoids too much talk of the situation in Tibet.

Britain has called for Liu to be released and Foreign Secretary William Hague called for greater autonomy in Tibet during a visit earlier this year.

However, Cameron is expected to tread softly on the issue of human rights during his 36-hour visit, disappointing critics of China's policies.

Cameron needs to make clear to his Chinese hosts that the UK won't soft-pedal human rights as the price for improved trade and business ties with China, said Phelim Kine, Asian researcher with New-York based Human Rights Watch.