After an eight-year battle, the White House has won the right for US Presidents to negotiate iron-clad trade deals that could have a significant impact on opening world markets.

Passage of a bill in Congress later this week giving the president "fast-track" trade authority will clear the way for multilateral talks on the World Trade Organisation's Doha agenda and the proposed hemisphere-wide Free Trade Area.

After intensive lobbying by President George W Bush and Republican leaders, the House of Representatives voted by a margin of three in the early hours of Saturday morning to give the President fast-track trade promotion authority. A majority in the Senate is assured.

The power to negotiate trade deals was held by five presidents until withdrawn by Congress in 1994. In future, Congress will not be able to amend trade agreements and will be restricted to voting for or against them.

Democrats and US trade union leaders have long opposed fast-track authority on the gounds that it enabled the White House to override concerns in Congress at job losses in American manufacturing and lowered environmental standards.

The defection of several New Democrats, who support free trade, gave Mr Bush one of his most important legislative victories by a razor thin margin. The vote was 215 to 212. The Senate has a three-to-one majority in favour of the measure.

The objections of organised labour were overcome when some Democrats secured subsidised health and training benefits for workers laid off through foreign competition. Democrats opposed the bill by 183 to 25.

The Bush administration now has a freer hand to negotiate more open markets around the world for US agricultural products, machinery and other products.

A final bill is expected to go to the president for signature later this week. The administration is expected to give first priority to agreements with Chile and Singapore to allow tariff-free trading.

US Trade Representative Mr Robert B. Zoellick hailed the White House victory, saying that America paid a price in the past eight years and had fallen behind other nations. Commerce Secretary Mr Donald Evans said the vote "sends a powerful signal to the markets in America."

AFL-CIO president Mr John J. Sweeney warned that Republican Congress members who supported fast-track would pay a price for their votes in November mid-term elections.

"Working people will hold them accoutable for their decision," he said.

Mr Bush claimed the deal would open markets, expand opportunities and create jobs for American workers and farmers.