Six days of world trade talks have begun in Hong Kong amid violent clashes between police and protesters.
World Trade Organization (WTO) members were quickly at loggerheads, with agriculture the main stumbling block.
Developing countries want richer nations such as the US and EU member states to cut both subsidies for their farmers and tariffs on imported foods.
UN Secretary General Kofi Annan said a failure to reform trade would be a disappointment to the world's poor.
There is little optimism among negotiators that a new general free trade agreement can be reached.
Critics have singled out the EU for refusing to make further concessions, but EU officials say that without concessions from other countries they can not go any further.
And some commentators say negotiations on reform to the global service sector may be put entirely on the back burner.
While some protesters tried to besiege the roads to the main conference centre, others - mainly South Korean farmers - tried to swim across Hong Kong harbour to the event.
"About a dozen managed to swim almost the whole way across," said BBC business reporter Steve Schifferes, who is in Hong Kong, "but several dozen police boats converged on the scene" forcing them to swim back.
The hundreds of protesters directly outside the conference centre dispersed after an hour's stand-off with police.
Earlier inside the conference hall, dozens of representatives of non-governmental organisations had staged a loud protest, unveiling a banner saying "No deal is better than a bad deal" in a number of languages.
They forced WTO boss Pascal Lamy to raise his voice to be heard as they chanted: "Development yes, Doha no", while he told the WTO representatives that the time had come to be "bold, open-minded and ready to take risks".
Protesters are starting to mass in great numbers
United Nation's Secretary General Kofi Annan called for an "unambiguous date for ending trade distorting subsidies".
He said trade negotiators had a duty to find the political will to move forward in the days ahead.
Failure, he said, would be a disappointment for people yearning to lift themselves out of poverty.
During the day thousands of anti-globalisation campaigners had protested across central Hong Kong, carrying huge banners, chanting and banging drums.
While riot police had to use pepper spray to hold back some protesters, the violence was said to fall far short of the levels seen during previous WTO meetings in Cancun and Seattle.
Seven protesters were injured and three of them were taken to hospital. Two policemen were slightly injured as well.
WTO members are hoping to reach an agreement at Hong Kong that would end the current Doha round of talks, and give the world's poorer nations greater access to the richest markets.
The core disagreement remains the agricultural impasse.
Poorer nations want the richer countries to drop subsidies because they say their producers cannot compete against the lower, subsidised prices.
They also want a reduction in the tariffs put on the goods they sell to richer countries.
In a change of tactics, the WTO has now said that it will focus the negotiations during the crucial week in Hong Kong on agriculture and the lowering tariffs for manufactured goods, where talks are also deadlocked, leaving the more complicated negotiations on the service sector for later.
The WTO also wants to get agreement on an EU-backed plan for a special development package for the world's poorest countries, the LDCs, which it hopes will gain their support for broader trade liberalisation.
If service sector negotiations do not succeed, then the main expected benefit of the trade deal for industrialised countries will disappear.
EU Trade Commissioner Peter Mandelson told BBC Radio 4's Today programme that he expected limited progress at Hong Kong.
"We're not going to do what we initially hoped to do at Hong Kong but nor need it be a disaster," he said.
"What I want to do is to make sure that we make valuable progress by agreeing the structure for the negotiations right across the board, not just in agriculture but in all the areas.
"[We need to then] intensify those negotiations in the early part of 2006 and then reach the grand bargain that we need to aim for."