More than 60 of the 103 firms polled by IRS believed equal pay audits should not be mandatory for private sector employers. One in four insisted salary structures that rewarded workers fairly regardless of their gender were attainable without formal audits.
But what are the reasons behind this refusal to look into the equality of pay scales?
A large part of this resistance seems to stem from their fear of what they will uncover, according to Stephen Bevan, managing director of the Work Foundation.
"When an employer uncovers how pay is distributed in all its forms, the result is often a culmination of years of tinkering with the system and years of compromised solutions and it's basically a bit of a mess," he said. "Like an embarrassing uncle, you'd rather not delve too deeply for fear of what you'll find."
The research shows such fears may be justified - of those survey respondents that have carried out audits, two in three found that men were paid more than women for work of equal value.
But Bevan said that not all employers were against audits for the same reason. "Some have a naïve belief that they won't find anything. They feel that they pay people equally and it's not an issue for them," he said.
However, many private sector HR professionals point to the cost and time involved in pay audits and insist there is no guarantee they will close the gender pay gap.
Sarah Churchman, internal director of diversity and inclusion at PricewaterhouseCoopers, said: "Equal pay, and mandatory pay audits, will not deliver equality at work.
"Pay data does not tell you if someone is at the wrong management level in a company, or that senior level positions are predominantly male, or provide equality in recognition of skills, progression rates and opportunities.
"If anything, mandatory pay audits could act to create complacency in the progression of women and recognition of their skills.
"What if all the senior roles are male? The glass ceiling will remain invisible with no incentive to remove it," she adds.
Sarah Williams-Gardener, director of Business in the Community initiative