Cases of the human form of mad cow disease are set to increase by about 20% each year, experts have predicted.

But scientists at the National CJD Surveillance Unit in Edinburgh stress numbers will still be very small.

In their latest report, they said the "north-south divide", where the incidence is higher in Scotland and northern England, will continue.

The report predicted there would be 32 deaths from the disease, the human form of BSE, this year.

The upward trend in vCJD cases continues to be statistically significant

CJD unit report

Scientists looked back at the history of vCJD since the unit was set up in May 1990 until December 2001.

It said 104 people were thought to have died from the condition, and a total of 114 cases had been identified by the end of January this year.

It suggested that people living in the north in 1991 were about one and three quarter times more likely to have developed vCJD.

'Significant cluster'

The report said: "The upward trend in vCJD cases continues to be statistically significant with an increase of 21% per year for onsets and 23% per year for deaths.

"The incidence of vCJD across the UK continues to show a north-south divide, with a higher incidence being maintained in the north of the UK."

But scientists stress the number of cases is small, and say the only "statistically significant cluster" of vCJD cases occurred in Leicestershire.

There, health officials suggested meat preparation techniques used by local butchers in the 1980s could have led to cross-contamination of muscle meat with brain tissue.

But Professor Peter Smith, chairman of Seac, the Spongiform Encephalopathy Advisory Committee, told BBC News Online: "They are the best estimates at the rate at which cases have been going up. But there is quite a lot of uncertainty."

Professor Smith added: "When vCJD was first described, people felt that, because so many people could potentially have eaten infected meat, that there could have been an epidemic of tens of thousands.

"But as time has gone on, that has looked far less likely."