Mr Blair wants to boost 'developed and developing' economies

He has acknowledged it will not be easy to secure an agreement to open markets to producers from the developing world.

Mr Blair was speaking at the Commonwealth summit in Malta, where talks have focused on trade reform.

Meanwhile, the Commonwealth meeting has called for a successful end to the WTO talks by the end of 2006 at the latest.

'Critical moment'

Mr Blair said: "For the poorest countries, whose labour costs are low but who often find the very high tariffs selling into the wealthy countries' markets, it is essential if they're to stand on their own two feet that they're allowed access into our markets.

"So if we fail at Hong Kong to move this on... we will do damage, not strangely just to the poor countries, though obviously that is one of the main purposes of this trade round, but we'll also damage our own country and other European countries.

"We'll damage the prospects in America and Japan. So this is a situation in which the wealthy world and the developing world has a lot to gain from trading with each other."

He said a successful conclusion to the so-called Doha round of talks could generate an extra �350bn ($600bn; 500bn euros) in trade a year.

Mr Blair also told ITV the trade round must not "fizzle out" after Hong Kong, and that there had to be "a strong set of tariff reductions on some of the goods and services that aren't to do with agriculture".

Sugar protest

Expectations of reaching a world trade deal before the deadline at the end of 2006 have been lessening in past weeks, with major political figures in Europe and the US saying differences may be too wide to bridge.

Talks had foundered in September 2003 before getting back on track in July 2004.

Mr Blair said a meeting in London next week of finance ministers from the G7 group of countries would be joined by other major trading nations, including Brazil, India and China, to focus on trade.

Trade inequalities were brought to the fore on Friday, when a number of Commonwealth Caribbean nations protested about a 36% cut by the EU to the guaranteed price of sugar.

Mr Blair said the EU, of which Britain holds the presidency, was looking at possible compensation measures.