With the world economy in the doldrums, a new trade pact covering goods and services would provide a much-needed shot in the arm, and success in Cancun is likely to be crucial for the current round of talks to be completed on time.

But scant progress has been made in the Doha Development round since its launch amid great fanfare in the Qatari capital in November 2001, leaving a string of missed deadlines.

Stubborn divergences remain in traditionally thorny areas such as reforming the global farming industry and opening up markets for industrial products, as well as over the launch of talks in new areas such as rules on investment policy.

However, ministers will be breathing a sigh of relief that a long-standing and highly emotional deadlock over sidestepping patent rules to allow poor countries to import generic medicines has been resolved.

WTO director general Supachai Panitchpakdi said the agreement had helped rebuild "the kind of trust that we need, that we saw at the launch of the round at Doha, that we will be needing for Cancun to succeed".

"I hope that this trust will remain with us to carry us through the Cancun difficult negotiation," he told a press conference after the 146 members sealed the deal on Saturday.

Ministers' discussions will focus on a draft declaration that has been crafted, though not universally agreed, by diplomats at WTO headquarters in Geneva listing key decisions.

The 21-page text represents envoys' best shot at forging common ground in various areas including agricultural subsidies, opening up markets for industrial goods and special provisions for developing countries.

The Uruguayan chairman of the WTO's ruling general council, Carlos Perez del Castillo, who drew up the draft text, stressed it was "without agreement in any part or in its totality."

But he added: "I think it constitutes nevertheless a manageable, working framework in which ministers can initiate their discussions in Cancun.

"It has the merits that it leaves a number of options open, and also that it focuses very clearly on the major areas of divergences," he told reporters on Saturday.

For the most controversial area, agriculture, the draft text covers the three so-called pillars -- market access, domestic support for farmers and export subsidies -- that have proved the hardest problems to crack.

But after WTO members missed the March target date for agreeing the guidelines on the agriculture talks, the draft ministerial declaration merely offers a framework, without figures, incorporating elements of a ground-breaking joint EU-US proposal.

The European Union and United States are the biggest subsidisers.

Big farming exporters of the Cairns Group, such as Australia and Brazil, and developing countries are pressing for reductions in the more than 300 billion dollars (274.6 billion euros) spent a year by industrialised countries on farm subsidies.

A clash is also likely over planned negotiations on new WTO rules on cross-border investment and competition policy, called for by the EU and Japan but opposed fiercely by developing countries led by India.