Trade ministers from the European Union, the United States, Brazil, India and Australia are to convene June 13 in Sao Paulo in a fresh bid to break a deadlock on agriculture that is threatening multilateral trade negotiations, a European source said Friday.

The meeting would be held during a gathering in Sao Paulo of the UN Conference on Trade and Development, he added.

A US trade official said after three days of talks here on agricultural trade that several important political questions remained to be

resolved.

The 147 members of the World Trade Organization are anxious to reach a "pre-agreement" on trade liberalization negotiations by the end of July. The talks are part of the overall Doha round of negotiations to eliminate global trade barriers that was launched in the Qatari capital in November 2001.

The round is scheduled to be concluded by January 2005 but progress has ground to a halt in disputes between developed and developing countries over trade in agricultural products.

A group of 20 emerging nations led by Brazil, China and India last

week proposed a formula under which customs duties on agricultural products would be lowered gradually, with the sharpest cuts reserved for the highest tariff levels.

The EU and the United States are ready to accept the proposal on condition that it is accompanied by a stipulation that products deemed especially sensitive for certain countries retain a higher level of tariff protection.

Another dispute centers on agricultural export subsidies in rich countries that distort trade and hamper farmers in developing nations trying to compete on world markets.