GENEVA (AFP) - World Trade Organization head Pascal Lamy is to invite ministers from 30 leading countries to a meeting here on July 21 to try to broker a final deal in the Doha round of trade talks, a diplomatic source said on Wednesday. Mexican ambassador Fernando de Mateo said: "Pascal (Lamy) told us that he thought we are in a good enough position to enter into a ministerial on the 21st (of July)." Lamy had spoken at a meeting here of the ambassadors of the countries concerned. The director general for trade at the European Commission, David O'Sullivan, expressed qualified optimism about the chances of success in concluding the talks which have stumbled from problem to deadlock since they began in 2001. He said: "I think it is perfectly imaginable that this deal can be made. But a lot of work needs to be done." The Doha round, aimed at a creating a new global agreement to remove barriers to trade and spur cross-border exchanges, has been deadlocked because of disagreements between the US and Europe and developed and developing countries. The round of negotiations involving 152 countries overall, and building on previous agreements to reduce barriers to world trade, should have been completed before the end of 2004. A central obstacle has been disagreement between countries in the northern and southern hemispheres on agriculture policies. Lamy said at the end of May that conditions to reach a final deal to complete the round had finally come together. Progress had been made on three central matters, he said: subsidies for agriculture, and customs duties on agricultural and industrial products. Lamy wants to move quickly to an agreement which can be put for ratification to the current US administration which will leave office in January. Officials at the WTO are concerned that attempts at ratification after that date might run into long delays. Only four days ago, Brazil and other developing countries complained that proposals on the table in the field of agriculture did not open up markets enough. "The options on the table do not seem to fulfil the mandate for substantial improvements in market access," the G20 group of developing countries said in a statement. The G20 blamed developed countries, saying: "we have no indication of what those countries are prepared to do" in terms of cutting subsidies.