Professor Liam Donaldson said the number of cases could range from a few hundred to many thousand.

But in a Ministry of Agriculture report, he also said the risk of catching CJD from eating beef-on-the-bone is "tiny and unquantifiable".

Professor Donaldson's findings will fuel the row between the government - which wants to lift the beef-on-the-bone ban - and the devolved Scottish and Welsh agriculture ministries, which are opposed to the move.

He made his recommendations seven weeks ago, saying the use of beef-on-the-bone in manufactured foods should still be outlawed because of the possibility that bone marrow is infectious.

Maintaining such a ban would also give consumers the choice of avoiding all beef-on-the-bone if they wished, he added.

BSE threat 'cut off'

In his report, which was released on Tuesday, Prof Donaldson said the six months since his last review of the situation had been "vital", due to the combined effect of two bans.

In August 1996 a ban on using animal protein in cattle food (the "clean feed watershed") was introduced alongside a ban on eating cattle older than 30 months.

Prof Donaldson said when the beef-on-the-bone ban was imposed in December 1997, infected cattle may have been still entering the human food chain.

But he stated that "currently, the oldest animals eligible for human consumption would have been born in February 1997, a full six months after the 'clean-feed watershed'".

He said in the past six months the bans combined to "largely cut off the threat to human food chain from cattle that had acquired BSE from infected feed".

Devolution row

Tough security regulations at slaughterhouses, cattle passports and tagging were also stopping cattle entering the food chain illegally, he said, while offspring culls were reducing the threat from inherited infection.

Agriculture Minister Nick Brown is meeting the German Health Minister on Wednesday in another effort to persuade the Berlin government to end its ban on British beef.

Mr Brown has said he will not lift the beef-on-the-bone ban until medical officers in Scotland, Wales and Northern Ireland agree it is safe to do so.

The Tories say the row highlights the problems caused by devolution.

But Mr Brown said it "makes more sense to proceed in an orderly way to lift the ban across the whole of the United Kingdom".