Legal firms must be shamed into returning fees taken out of compensation for ill former miners, a Labour peer is to tell the Prime Minister.
Lord Lofthouse, who will present a report to Downing Street on the extent of the practice, said it was "appalling" individuals were not getting their full payouts.
The peer, himself a former miner, said he had discovered two firms had made £100 million out of the official Government-paid fees for taking cases.
"But they haven't been satisfied with that; they've been taking money out of miners' compensation," he told BBC Radio 4's Today programme.
"Some of them have been keeping it themselves I understand, and others have been passing it on to claim farmers, that's people that's been directing these poor, sick, unfortunate, elderly miners to these solicitors and they've been having the rake-off. I think it is appalling."
Billions of pounds has already been paid out under the scheme to ex-workers suffering respiratory diseases and conditions such as vibration white finger.
But Lord Lofthouse said many "only get a pittance" and were unaware a share of it had gone to lawyers.
"If there's been a decision on a certain amount of money for compensation for a particular individual, all that money should go to the miner," he said.
He said he wanted Tony Blair and Chancellor Gordon Brown to "go into it thoroughly" and identify all the cases concerned "so we can take it up with the Law Society or the individual solicitors and hope they will be so shamed that they pay the money back".
Peter Williamson, chair of the Solicitors Regulation Authority, told the BBC: "I'm ashamed that solicitors whose costs are being met by the Government should do such a thing. Solicitors are supposed to put their clients' interests first, and that is a fundamental, professional principle."
