The Pensions Regulator (TPR) has received 60 whistleblowing reports over potential auto-enrolment inducement offers.
Under auto-enrolment rules, employers are not allowed to offer staff higher pay as an incentive to opt-out of a pension scheme.
Those that are found to have offered such an inducement can be fined by TPR and could even face criminal proceedings.
The rule has come under scrutiny this month, after the NHS Pensions Board referred Oxleas NHS Foundation Trust to TPR over a pay deal which offered new nurses a higher salary if they opted out of the NHS pension scheme.
Giving evidence to the work and pensions select committee as part of its inquiry into auto-enrolment, TPR chief executive Lesley Titcomb (pictured) said 60 whistleblowers had come to the regulator to report concerns about potential inducement deals.
'At the moment I think we've had about 60 whistleblowing reports,' she said.
Titcomb said around half of these reports led to a further investigation.
'We follow up on each of those on a case by case basis. Some of them prove to be not an issue, others are worthy of further investigation, and I think about half of those have gone into a more detailed investigation,' she said.
TPR can issue £400 fixed penalty notices to those doing inducements, and if the employer fails to put the matter right the regulator can then use escalating penalties. Where a criminal offence has been committed prosecution is also an option.
Charles Counsell, executive director of auto-enrolment at the regulator, added that employers offering inducements tended to immediately comply with the regulator's orders.
'The truth of it is that should this happen, employers tend to say "oh, okay, I'll put it right" and that in the end is a better answer,' he said.
'We have completed our first investigation, and the employer put right what had gone wrong.'