Opra announced the criminal proceedings as it published details of numerous breaches of pensions law, uncovered since it started work in April last year, including several cases which strongly resemble the actions of Robert Maxwell.
The prosecuted employers, which Opra cannot name for legal reasons, are expected to be forced into court before the end of March. They are being prosecuted for failure to pay members' contributions into pension schemes.
John Hayes, Opra's chairman, said: "The cases concern the continuing failure by some employers, without reasonable excuse, to pay over deductions made from employees' pay packets into the employees' occupational scheme. We have given public warnings on a number of occasions about the seriousness with which we regard such conduct."
The regulator, which can act only when whistleblowers report pension abuses, said a third of its inquiries had been about failure to pay. Further unreported offences are also likely to have occurred.
In many cases, employers were putting off paying contributions until more than three weeks after paying wages. In some cases, employers were failing to pay altogether. Opra is treating the initial court cases as a test. If they are successful, more criminal proceedings are expected.
Mr Hayes said the regulator had been soft with employers until now because of the difficulties they have had in meeting the tough requirements of the Pensions Act, which came into force last April.
"In future, the board of Opra will not be taking such a lenient course. Among the factors we will take into account when we consider a scheme's failure to comply will be the speed with which breaches are put right; the co-operation we receive; the track record of the pension scheme; and whether members' interests have been jeopardised."
The extent of failure to pay has shocked the pensions industry.