Protesters with bamboo sticks broke through police lines, until they were forced back with tear gas and batons.

Nine hundred demonstrators have been penned in by police on a road but their protest continues. Police say they "will be handled according to the law".

Police say 41 people, including five officers, have been injured in clashes.

Talks have failed to agree on a firm date for ending farm export subsidies, the draft summit declaration shows.

The US and developing states wanted a 2010 deadline, but the EU has rejected this.

The commitment to open up service markets stays in the draft, despite complaints from some developing states.

The six-day talks are due to end on Sunday, but some delegates from the 149 states have threatened to walk out if their concerns are not addressed.

Brazil has said it does not think trade talks will be able to take the process much further, and has pledged to renew its call for a summit of world leaders.

"There is a need to inject political energy into the negotiations," Foreign Minister Celso Amorim said, following the release of the draft text.

Escalation

Protesters led by South Korean farmers - among the most heavily subsidised in the world - had vowed to step up action against the world trading system on Saturday.

Police chief Dick Lee said about 1,000 protesters had suddenly broken off from an official march and charged a cordon keeping them away from the convention centre.

"A major confrontation ensued," he said, in which protesters fought police with iron poles, and broke through barriers.

A senior government official appeared on television to warn people to avoid the unrest, the worst in Hong Kong since angry protests erupted after the crackdown in Beijing's Tiananmen Square in 1989.

Later police said they had regained control.

A BBC News website correspondent on the scene reported that at 2300 (1500 GMT) a non-violent stand-off was continuing between police and protesters on the Gloucester Road near the Hong Kong Convention and Exhibition Centre in the Wanchai district.

The demonstrators were chanting anti-WTO slogans and appeared ready to stay all night.

'Disgrace'

The protests came as delegates studied the text of the draft agreement, which has been condemned by some developing countries for not addressing their concerns.

Many feel they are being pressed too hard to allow foreign competition in service industries.

And some are also likely to be disappointed by the lack of progress on a plan to give duty-free and quota-free access to exports for the world's least-developed states.

Some African countries have been seeking the elimination of subsidies for rich-country cotton farmers.

The draft stops short of that, suggesting instead that they should be cut further and more quickly than for other farm products.

But the draft text asks rich states to scrap export subsidies for cotton by 2006, to help West African producers.

However, the EU has none and the US is already in the process of eliminating its main cotton export supports.

Relief agencies criticised the draft.

ActionAid called it a "a disgrace and an insult to poor people all over the world".