Swiss Economics Minister Joseph Deiss says there is still much to do to make a success of a major World Trade Organization (WTO) meeting in December.
The aim of the ministerial summit, which will take place in Hong Kong, is to put the finishing touches to the Doha round of talks on lowering trade barriers.
But negotiations have been bogged down for a considerable time over differences in agricultural policy.
Deiss was in Geneva on Tuesday and Wednesday to measure the state of play with about 20 other ministers at the WTO headquarters.
"We do not want to lower the aims of the Doha round. But we have to be realistic. Important differences remain, not only in agriculture but also in industrial products," he said.
Luzius Wasescha, chief Swiss negotiator at the WTO, sought to dampen expectations of a breakthrough by the end of the year.
"We are aware of the big gaps among the positions of members... and we have to envisage that we may not be in a position to achieve everything in Hong Kong," he told swissinfo.
Some countries have already conceded that there is too little time to reach an agreement before December and that a second global trade summit might have to be called for early next year.
But Wasescha said it was "too early" to speculate about the need for a follow-up meeting.
"Let us first see what we can achieve in Hong Kong. Even in trade policy sometimes miracles are possible."
Subsidies and tariffs
Switzerland, along with countries including the United States and Japan, has been under mounting pressure from developing nations to reduce farm subsidies and cut import tariffs on agricultural products.
But the G10 group of net agriculture importers, coordinated by Switzerland, is insisting on flexibility and exceptions when it comes to so-called "sensitive" products.
Deiss said it was "difficult at this stage" to foresee "any progress between now and Hong Kong" on the agriculture dossier.
Wasescha pointed the finger at the world's leading agricultural exporters, describing them as the "biggest stumbling block" to an agreement.
War of words
In a sign that consensus-led dialogue is being replaced by an increasingly heated war of words, Australia's trade negotiator on Wednesday lashed out at Switzerland, Norway and Japan, branding them "intransigent" in negotiations and attacking their defence of protectionist policies as an "obscenity".
"This just shows how far Australia is from the substance," responded Wasescha.
"We can only achieve the Doha mandate if we show flexibility... because among 148 member states you have about 120 different situations in agriculture."
Switzerland has also been criticised in other quarters for its stance on agriculture.
Earlier this week Swiss economics commentator Beat Kappeler told swissinfo Bern was "damaging its free-trade credentials" within the WTO for the sake of a sector which accounts for only 0.5 per cent of the country's gross domestic product.
But Wasescha defended his negotiating position, saying that "as long as the exporters of agricultural products take the whole process hostage we can do nothing else but concentrate on agriculture".
"We are attached to the free-trade idea and we fight for fairness... but the present negotiating surroundings are anything but fair."
The sixth WTO ministerial conference is to be held in Hong Kong from December 13-18.
In general, ministerial conferences are the WTO's highest decision-making body, meeting at least once every two years and providing political direction for the organisation.
The sixth conference is considered vital for enabling the four-year-old Doha Development Agenda negotiations to make sufficient progress to conclude the round in 2006.
WTO Director-General Pascal Lamy has described Hong Kong as the "last and best chance" to conclude the Doha round by next year.