Key trade ministers meet in London at the weekend under growing pressure to reach a deal in global free trade talks, but diplomats warned today against expecting a breakthrough. U.S. Trade Representative Susan Schwab, European Union Trade Commissioner Peter Mandelson, Brazil's Foreign Minister Celso Amorim and India's Trade Minister Kamal Nath will hold separate bilateral discussions, following the approach adopted in recent talks among their senior officials. "Several more meetings at all levels will be required before we can talk of breakthroughs," Reuters quoted one senior EU official as saying. It will be the first time that the four, who have been taking the lead in the search for common ground, have met since the World Trade Organisation (WTO) agreed in late January to relaunch its Doha round of trade liberalisation negotiations after a six-month suspension. The negotiations, dogged by deep divisions over agricultural trade, were halted by WTO chief Pascal Lamy because he saw no way at the time of bridging the gaps. Lamy says the WTO has a brief window of opportunity to secure agreement on a blueprint for a deal. If the chance is not taken, the five-year-old round could collapse, undermining confidence in the global trading system. After the weekend, ministers will be in Geneva on Monday and Tuesday to meet Lamy who is facing discontent in the 150-state body that members are being kept in the dark about the progress, if any, that the major powers are making. Business leaders in developed countries have become more vocal in calling for a deal. German Chancellor Angela Merkel and British Prime Minister Tony Blair have both spoken out strongly in favour of a Doha accord. Launched in late 2001, the WTO talks have been billed as a once-in-a-generation chance to boost the global economy and help lift millions out of poverty through trade.