The Legal Action Group (LAG) and Law Centres Federation (LCF) have called on the Lord Chancellor, Lord Irvine, to extend regulation to cover "cowboy" employment law advisers, who take on contingency fee tribunal cases without being legally qualified.
Both organisations want regulations to be included in the legislation which will be announced in this week's Queen's Speech.
Lawyers expect the speech to include legislation on conditional fee agreements. But the LCF has joined LAG in calling for Lord Irvine not to exclude tribunals.
The two group's fired off a letter to Lord Irvine and the Legal Aid Board last week, which called for the regulation of conditional and contingency fee use in employment tribunals.
LAG policy director Vicki Chapman said: "We'd like the Government to use the opportunity of introducing legislation on conditional fees to regulate other areas where contingency or conditional fees are used."
Chapman said: "People can be severely ripped off by cowboy practices."
Chapman said LAG wanted the Government to put a statutory limit on the amount of damages the consultant could take from client damages. She said LAG had first called for the regulations in its response to the Government's Access to Justice with Conditional Fees consultation paper in March, but had received no reply.
Law centres and employment lawyers have reported an increase in the number of non-legally qualified consultants offering tribunal representation on a contingency fee basis - for which legal aid is not available.
Tony Pullen, an employment barrister at Hammersmith and Fulham Law Centre, said consultants routinely took at least a third of their client's damages, even though employment tribunal awards have a ceiling of £2,500 and clients pay their own costs.
Pullen said consultants frequently missed out important arguments or "left clients high and dry by refusing to represent them at the eleventh hour".