Busy personal injury solicitors registered more than 20,000 mining health cases in just eight hours last Wednesday, as the midnight deadline for lodging respiratory disease claims loomed - and the total number of claims has now topped half a million.

Figures from the Department of Trade and Industry (DTI) showed that 555,000 respiratory disease claims and 227,000 claims relating to vibration white finger have been registered since it launched its coal health scheme in 1999; the DTI now expects to pay out 1.9 billion in damages.

The number of claims averaged 14,000 weekly until the 31 March deadline for registering respiratory claims was widely publicised recently - and then the number rocketed to 23,000 per week.

A DTI spokeswoman said: 'Nearly 20,000 new claims were registered between 4pm and midnight [on 31 March] alone.'

Anthony Patterson, national co-ordinator for British coal litigation at trade union firm Thompsons, said it had manned some of its offices until midnight to cope with the last-minute rush.

'We registered the last claim at six minutes to midnight - so after six years of the scheme we had six minutes to go,' he said.

However, Mr Patterson said he expected that evidence would arise showing that a vast numbers of claims had slipped through the net - including cases that were left unregistered because claims farmers had not been able to sell them on to law firms.

Mining claims have proved to be a lucrative area for personal injury firms, with some having profited by more than 35 million.

However, the scheme has provoked criticisms from MPs that some solicitors were overcharging; this caused the Law Society to relax its complaints procedure at the beginning of this year.

A Society spokesman said it has received 154 complaints so far, 59 of which have been resolved.

Paula Rohan