There has been a last-minute hitch in a deal to end farm export subsidies. Brazil has refused to agree to a cut-off date of 2013 offered by the European Union at the World Trade Organisation summit in Hong Kong.

EU spokesman Peter Power said: "We have made a major effort to save these talks. We have proposed an end date for the elimination of export subsidies. However the goalposts moved at the last moment and we are now informing the member states of the situation."

The US and developing countries had been angling for a cut-off date of 2010. Meanwhile, Hong Kong saw its worst violence for years as protesters clashed again with police in the streets, coming within 30 metres of the conference centre.

Nearly 100 people were injured. Officers used tear gas, batons, pepper spray and fire hoses to hold back the crowds, many of whom are farmers from South Korea who say free trade is ruining them. Some 900 people have been arrested.

But organisers say two huge planned marches for later today will still go ahead.

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