LONDON China on Monday threw its weight behind the United States and other farm-producing countries demanding that the World Trade Organization (WTO) agree a deadline for ending agricultural exports subsidies.

Export subsidies are one of the thorniest issues facing the WTO, where negotiators from the 144 member states began four days of closed-door talks on farm aid, part of a global round of trade negotiations.

The United States has called for subsidies to be wound up within five years, while other agriculture exporters are looking for an even tighter deadline.

But any attempt to set a firm time frame is being resisted by the European Union, which says that subsidies cannot be negotiated separately from other aspects of farm trade, including export credit programs.

China, laying out its position on the farm issue for the first time since joining the body at the start of the year, backed a call for developed countries to be given three years to end their export subsidies, with poorer states getting six years, Reuters quoted diplomats as saying.

The clock would start running from 2005 when the WTO hopes to conclude the negotiations -- launched last November in Doha, Qatar -- to free trade in a wide range of services and goods, including agriculture.

WTO Director General Mike Moore has warned that agreement on agriculture is fundamental to the success of the Doha Round, which officials say would give a multi-billion dollar boost to world trade.

Apart from subsidies, negotiators are also due to touch on other issues of farm trade, including domestic support programs and food aid, during the talks which end on Thursday.