The majority of employers have no plans to check that they pay women fairly, according to an Equal Opportunities Commission (EOC) report.
The study shows that 54 per cent of large and 67 per cent of medium-sized employers have no plans to carry out pay reviews.
The research, carried out for the EOC by the Institute for Employment Studies, also reveals that secrecy over pay is widespread.
More than a fifth of employers do not allow employees to share information about their pay with colleagues.
Commenting on the findings, Julie Mellor, chair of the EOC, warned that complacency and secrecy were threatening to halt progress on equal pay and urged all employers to review their pay systems to check for bias.
She said: "The level of complacency and secrecy this research has uncovered is staggering. Employers have a crucial role to play in tackling unequal pay. Although some have accepted that responsibility willingly, many others still don't seem to have got the message."