The cull was the basis of the deal struck at the Florence summit in June. In that deal, other EU countries agreed to a stage-by-stage lifting of the ban, and John Major agreed to end his policy of non-cooperation with EU institutions. But over the summer, Conservative MPs made it clear they would not support the Government in the Commons vote next month to authorise the extra cull, of 125,000 younger cattle.
Mr Major was provided with a figleaf for his retreat by an Oxford University study published last month.
This suggested that many more BSE-infected cows had been sold for food than previously estimated. But it also predicted that BSE, or "mad-cow disease", would dwindle almost to extinction by 2001.
Mr Major also cited new evidence that BSE could be passed from mother to calf as a reason for re-examining the cull - although previously Angela Browning, the junior agriculture minister, had implied that this might mean that more cows, rather than fewer, would have to be slaughtered.
"So those are two new material facts," said Mr Major, on tour in the West Country. "We have to consider them. There is no pre-ordained outcome. What we are doing is considering it and we will no doubt wish to consult with the European Union and then we will make a final decision."
But a European Commission spokesman said yesterday: "We always knew that BSE was going to disappear in five or six years. The reasoning behind a selective slaughter plan is to reduce the incidence of the disease and therefore give the consumer better protection."
A spokesman for Franz Fischler, the Agriculture Commissioner, warned Britain to honour its commitment to the selective slaughter of high-risk cattle. "The selective-slaughter plan was an integral part of the Florence agreement," he said.
"The step-by-step approach to the lifting of the ban was dependent on the selective-slaughter plan."
The main opposition parties quickly seized on the Prime Minister's embarrassment. Gavin Strang, Labour's agriculture spokesman, described the Florence deal as "lousy". He said: "The Government had pledged the slaughter of around 120,000 cattle. In return, they did not even bring back a timetable for the lifting of the beef-export ban, and nor did they bring our farmers any guarantees that any future agreement would be reached on any of the steps towards the lifting of the ban."
Paul Tyler, for the Liberal Democrats, welcomed moves to reduce the cull: "Ministers are realising that there is no point in a mass-slaughter scheme if it neither speeds up the eradication of BSE, nor opens the export doors again."
And Mr Major also came under fire from the internal opposition Redwood Party. John Redwood, the former Tory leadership challenger, said he hoped the Government would be able to negotiate a better deal - killing fewer cows, while lifting the export ban.
"There is no point in killing cows that we think should not be killed unless that action gets the beef ban lifted," he said on BBC Radio 4's World at One. "If there is no prospect of the ban being lifted, the best we can do is to look after our own farmers and domestic market and there is every reason for not killing all these cows unnecessarily. We should kill that number which our own scientific advice and judgment says is correct."Reuse content