There is still a significant gender gap in UK pensions, with women expecting their annual retirement income to be a third less than men.

According to new research, women in Britain typically anticipate annuities of £12,250 a year after retiring, while the average man expects a yearly income of £18,000. The gap - £5,750 - is actually smaller than last year, when it was £6,500.

However, the Class of 2012 report suggested that this narrowing inequality was due to lowered expectations among men, rather than higher estimates on the part of women.

The study, by Prudential, revealed that women's annual retirement income prospects dropped by £650 between 2011 and 2012, while men's fell by £1,400 in the same period.

Although the pension gender gap is smaller now than it has been in any of the last three years, men and women's expectations have both fallen dramatically during the course of the recession. In 2009, women expected an average retirement income of £13,671 and men £20,313.

Worryingly, nearly half of women who answered the survey said that they do not expect to have enough income for a comfortable retirement.

Responding to the report, Dr Ros Altmann of over-50s specialist Saga, said that state and private pensions have both historically worked more in favour of men than women.

She explained that one of the reasons for this is that part of the state pension is related to earnings and women still tend to earn less than men.

People are eligible for the Additional State Pension if they are employed and earning more than £5,564 a year from a single job; looking after children under 12 years old and claiming child benefits; or caring for a sick or disabled person for more than 20 hours a week and claiming carer's credit.

However, Saga estimates that the normal weekly entitlement from the Additional State Pension is just £12 for women, less than half of the £28 typically received by men.

The group explained that private pensions also tend to be less for females because they often earn lower wages and have traditionally worked fewer years as a result of taking time off to raise children.