"I have said before that my finger was hovering over the alarm button. Now I have pressed it," Panitchpakdi told the WTO's 148 member states in a meeting of its top negotiating body.

Trading nations have been trying to come up with the broad outline of a possible agreement on further trade liberalisation by the end of the month, but there is growing concern about the slow pace of the largely technical talks.

"Every day the crisis of immobility deepens," Supachai added, casting doubt over the ability of the negotiators to come up with a deal on a new round at a ministerial conference in December 2005 at their current pace.

"There is a very great deal left to do in the autumn in order to have a worthwhile result at Hong Kong," he said in the written copy of his speech behind closed doors.

A meeting of the WTO's top decision making body, the General Council, on July 27 to 29 is due to make a last negotiating push before the summer break.

It is regarded as a key stage on the road to the Hong Kong meeting, as the WTO seeks to avoid a a repeat of the failure of the last ministerial meeting in Cancun, Mexico, in 2003.

The breakdown of Cancun opened up a rift between rich and poor countries froze the talks underway since 2001, which are meant to bring down more trade barriers mainly to the benefit of developing countries.

Supachai said there was still a chance for some "worthwhile advances" by the end of next week.

Key issues include agricultural tariffs and export subsidies, mainly in wealthy nations, industrial tariff barriers, and special treatment for the poorest countries.