Ministers from around the world are meeting in Paris on Wednesday, hoping to salvage global trade talks.
Many in developing countries remain suspicious of the WTO
Three months remain till a key deadline for the so-called "Doha round" of talks, which began in 2001.
Subsidies paid to farmers in Europe, the US and Japan are still a stumbling block, as poorer states say they are shut out of key markets.
On Tuesday, campaigners accused Europe of deploying "delaying tactics" over the subsidies.
But rich countries say that in exchange for loosening farm subsidies, they need to see better opportunities to export services to the developing world.
Back from the brink
The talks in Paris are taking place on the sidelines of the Organisation for Economic Co-operation and Development, the 30-member club of industrialised countries.
They are intended to lay the foundations for agreement on an outline deal by July, ahead of a full-scale WTO summit in December in Hong Kong.
The WTO had hoped to complete the Doha talks - intended to focus on the needs of developing countries - by the end of 2004.
But the breakdown of talks in September 2003 at the Mexican resort of Cancun put paid to the timetable, as an alliance of developing countries, the G-20, flexed its muscles against the traditional dominance of the US, the EU and Japan.
An initial draft deal was reached in August 2004, promising to phase out much of both the domestic payments made to US and Japanese farmers and the export subsidies more prevalent in the EU.
Now, however, the timetable is again becoming tight.
"The time is over for bickering about which component of the negotiations moves first or fastest," wrote EU Trade Commissioner Peter Mandelson in the Financial Times on Wednesday.
"We need, by July, a rough approximation of what a Doha undertaking might look like, so that we can put flesh on the bones."
But Tuesday night brought fresh disagreement as Europe dug in its heels over import duties on farming products.
It vetoed a possible deal on how to translate tariffs quoted in currencies into percentages.
Although the dispute was technical, the formula in question is vital to any agreement on cutting tariffs.
Both poorer countries such as Brazil, and rich agricultural exporters such as Australia blamed the EU for the hold-up.
"These negotiations... were very technical, but today they turned out to be very political as well," said EU Agriculture Commissioner Mariann Fischer Boel.