Two years after the last bid to get global trade talks going collapsed in Seattle's streets, negotiators began trying again Friday with a global recession replacing protesters as the principal threat.

The five-day meeting of the World Trade Organization in this tiny desert emirate will accept the membership of the world's most populous country, China, on Saturday after 15 years of negotiations. Taiwan will be approved a day later.

But the main focus is on whether differences that sank the 1999 Seattle talks, like farm subsidies in the rich West, and new ones, such as access to medicines for the poorest countries, could be overcome to reach consensus on launching new negotiations.

Those pushing for a new round said success would send a strong signal of confidence in the world economy and of solidarity in the aftermath of the terrorist attacks on the United States.

U.N. Secretary-General Kofi Annan, in a statement delivered to the conference, said a global recession would be "devastating'' for the world's poor.

"To halt and reverse this trend we must restore market confidence, create new export opportunities and resume growth,'' he said. "Now, more than ever, we need to resist the siren voices of protectionism and work out multilateral solutions to our problems.''

U.S. Trade Representative Robert Zoellick said it was "a critical time for cooperation and moving forward, not isolation and retreat.''

Even before the opening ceremony, Zoellick met with ministers from African members of the WTO and with Asian ministers and emerged saying he was "encouraged.''

He also stressed that the meeting's mission was not to solve all of the problems.

"Our role here is to launch new negotiations, not to complete them,'' he said.

If a new round is launched, it will likely last for years. The last talks, called the Uruguay round after the country where they were approved, finished in 1994.

With the United States and Europe closer on many issues, the big question is whether they can persuade developing countries - the majority of the WTO's 142 members - to sign on.

High among their concerns are reconciling the protection of medical patents with ensuring affordable access to medicines to deal with AIDS and other health crises.

Developing countries led by Brazil and India want a declaration that nothing in the WTO's agreement will prevent governments taking action to protect public health.

But countries with big pharmaceutical industries fear that could lead to patents being swept aside too easily, and are resisting any change.

"It's the most difficult issue we've got,'' said Baroness Symons, British junior trade minister, following a meeting with her Brazilian counterpart, Sergio Amaral.

"We need to ensure that poverty does not of itself exclude people from lifesaving medicines,'' she said. "But we do have to ensure we don't give away the really important generating power of the pharmaceutical companies for medicines of the future.''

Japan and the European Union also are under pressure from the developing world for refusing to eliminate farm export subsidies, which poorer nations say their own producers can't compete against.

Other big food-exporting nations, including Canada, Australia and Argentina, also are pushing hard for any talks to aim at phasing out such subsidies.

The EU insists export credits - used primarily by the United States - be disciplined as well.

"Europe has moved, Europe is willing to go the extra mile, but Europe can't do it alone,'' EU Trade Commissioner Pascal Lamy said.

Demonstrators, who have been mostly unable to get to Qatar because of strict visa regulations, are planning protests and anti-WTO events in cities across the globe during the conference.

The Emir of Qatar, Sheik Hamad bin Khalifa Al Thani, reminded delegates at the opening ceremony that the world was watching.

"A successful meeting will be the best demonstration that all nations - rich and poor alike - are working together for a better and more just world,'' he said.