Zoellick, in a letter sent to the almost 150 countries that belong to the trade organisation, said the United States was prepared to make a serious effort to get talks going, the official said on Sunday, but declined to provide details.    

"The letter suggests that WTO members should focus on the basics, especially the core market access topics of agriculture, goods, and services," said the official, who did not want to be named.

The talks are aimed at lowering or eliminating tariffs charged by countries around the world on imported goods and services, thereby lowering the costs of those products to consumers.

The official said the US trade ambassador asked trade ministers to agree by the middle of the year to terms for a fresh start to talks that broke down in September last year in Cancun, Mexico, over agricultural issues.

"The period after Cancun was a necessary collective catching of breath, and now we must all recommit to pushing forward. We have chance to surprise the naysayers," the official said.

Many developing nations are hindered in exporting farm products to industrialised nations by trade obstacles aimed at shielding farmers and ranchers in those countries from being driven out of business by cheap imports.

Zoellick believes no trade deal can be sealed without the complete elimination of agricultural export subsidies, the trade official said. That position is likely to be difficult for the European Union to accept.

The talks, launched in Doha, Qatar in late 2001, were to have wrapped up by the end of 2004. Zoellick asked trade ministers to be ready to meet in Hong Kong before the end of the year, the official said.