The Equal Opportunities Commission is calling for the tightening of rules on underwriting of insurance products where men and women are offered different rates.
The EOC, which opposed an EU attempt to ban gender-based underwriting, wants insurers to be able to offer different rates on grounds of sex only if they have relevant and up-to-date data to justify the difference.
An EOC-commissioned analysis of annuity rates by the Pensions Policy Institute shows the introduction of unisex rates would not have a significant benefit to women.
The report says less than a quarter of pensioners have annuities and gains and losses on annuity rates would only have a small effect on retirement incomes of women.
It adds that although unisex annuities would see women's annuities rise by 10 per cent and men's drop by 3 per cent, a high proportion of women would see a drop in income because they are wives or widows of male annuitants.
The EOC has called for a professional regulatory body to monitor how companies are assessing risks.
Chairwoman Julie Mellor says: “Women's average retirement income is just 57 per cent of men's and the lower return they get on an annuity does contribute to that gap for some women. The current law is far too vague. We want to make sure that insurers can only treat men and women differently if they can demonstrate very clearly differences in risks that can only be explained in terms of gender.
PPI director Alison O'Connell says: “Rather than introduce unisex annuity rates, it might be more beneficial to have access to better advice and a greater ability to shop around.”