One in ten (11%) of The Pensions Regulator's (TPR's) 590 investigations into auto-enrolment (AE) non-compliance was triggered by whistleblowing reports.
This month, a Professional Adviser's sister title Professional Pensions Freedom of Information request revealed more than 500 inquiries had been launched into employers' AE measures in the last six months.
The regulator has now clarified a total of 65 investigations were opened as a result of reports from whistleblowers.
A statement from TPR said: "From 1 April 2012 to 31 Jan 2014, there have been 590 investigations conducted by TPR into employers who were either experiencing difficulties with or had failed to comply with the employer duties; 65 of the investigations were instigated by whistleblowers.
"This relatively low level of investigations prompted by reports from whistleblowers (11%) is in line with our expectations as the investigations to date have largely concerned large employers who are mainly compliant in nature."
The remaining cases followed proactive action from TPR, as well as small employers that contacted the regulator with concerns prior to staging or wished to bring forward their staging date.
TPR previously said it would rely on whistleblowing and spot checks to police AE, ahead of the policy's launch in October 2012.
In November, TPR's DC code of practice and compliance and enforcement regime came into effect, which will see TPR proactively target areas of risk through thematic reviews, in addition to investigating whistleblower concerns.
'Necessary steps' taken
Penalty payments and enforcement policy
Fees as low as 0.04%
Only 9,486 applied for the benefit in 12 months
Women and young people adversely affected