Ministers from about 35 countries have failed to make a breakthrough in the World Trade Organisation's (WTO) Doha round to open up global trade. Talkd to broker a new global trade pact have collapsed because key powers are unable to bridge their differences on food tariffs, the head of the World Trade Organisation (WTO) says. "There is no use beating around the bush, this meeting has collapsed, members have simply not been able to bridge their differences," WTO Director-General Pascal Lamy said. Several delegates still maintained that in light of what had been accomplished in trade talks to date, further moves to salvage the negotiating process would be justified. But for the moment, momentum has ground to a halt. Lamy said that time was needed before the 153 members of the WTO could decide on how to proceed. "We will need to let the dust settle a bit, it's probably difficult to look too far into the future at this point," he said. "WTO members will need to have a sobre look at if and how they bring the pieces back together," he said. US Trade Representative Susan Schwab said hopes for a breakthrough had been dashed. "The package that we were able to negotiate and agree on Friday night is not going to carry the day," Ms Schwab said as she left a meeting of key trading powers, referring to an earlier breakthrough on a deal proposed by Lamy. Ministers had struggled for more than a week to reach consensus on subsidy levels and import tariffs for a new deal under the World Trade Organisation's Doha Round, which has repeatedly foundered since its launch seven years ago. Delegates said negotiations stumbled on proposals for so-called SSM measures to protect poor farmers that would have imposed a special tariff on certain agricultural goods in the event of an import surge or price fall. "They (the US) have refused to move on SSM. It is an issue of vital importance to us," an Indian diplomat said as today's meeting of seven key countries dissolved. The world's economic superpower, the US, and India, one of the world's biggest emerging economies, are sharply divided over the SSM - the special safeguard mechanism. "The US and India did not accept the compromise proposals, and arrived at an impasse," a source close to the talks said, adding that the negotiations had broken down. Some developing countries such as India wanted the mechanism to kick in at a lower import surge level than has been proposed in order to protect their millions of poor farmers from starvation. Others wanted it to take effect at a higher rate so as not to hurt exporters.