The meeting, bringing together Brazil, India, the EU and United States, will try to bridge differences, notably over farm subsidies, which have hampered efforts to keep almost four years of World Trade Organisation negotiations on track.

The 148 nations in the WTO are up against the clock: a crucial summit in Hong Kong in December is meant to produce at least the bare bones of an accord on cutting customs duties, subsidies and other barriers to commerce.

But without a deal among the giants of world trade, the outlook for Hong Hong is bleak -- and that could mean the talks will be mired for years, experts say.

"The pressure is on these four members, and the outcome of the meeting will be a good sign of the ability of the WTO to move forward in coming weeks," said a Geneva-based trade diplomat.

The "Gang of Four" -- the term used by new WTO chief Pascal Lamy -- are set to meet Friday morning at the Brazilian embassy in Paris.

The discussions will bring together Brazilian foreign minister Celso Amorim, who steers his country's commercial negotiations, US trade chief Rob Portman and his EU counterpart Peter Mandelson, plus India's commerce minister Kamal Nath.

Last week, Lamy said that at least two-thirds of the issues under negotiation must be settled by Hong Kong.