The family planning service Marie Stopes International said today that it performed a record number of UK abortions last month.

The charity carried out nearly 6,000 abortions at its nine centres across the UK in January, the highest number in its 32-year history. This was a rise of 13% on January last year.

The charity's UK director, Liz Davies, blamed the surge in abortions on excess drinking over the Christmas season.

"We may be seeing the consequences of the festive season, when partying and excess alcohol consumption combine to increase libido and lower inhibition, with the inevitable consequence of unprotected sex resulting in unplanned pregnancies."

Ms Davies said the "biggest ever rise in abortion figures in the month after Christmas" came despite its campaign that encouraged women to obtain the morning after pill before the festive season.

She called on the government to run a pre-Christmas public awareness campaign similar to those for drink driving.

"There is a clear case for an annual government-funded national education campaign to alert women and men to the importance of preventing unwanted pregnancies and sexually transmitted infections including HIV/Aids," she said.

Ann Furedi, chief executive of the British Pregnancy Advisory Service (BPAS), rejected the link with Christmas festivities. "We've also seen a higher than usual number of women for abortion treatment this January, which is traditionally a time of high demand. However, we think the increased figures may reflect a difficult struggle to access proper services, rather than the result of women being 'careless after boozy office parties'."

"Drastic NHS spending cutbacks are resulting in well-documented delays to abortion in some areas. It may be due to that treatment bottleneck, that the treatments have been clustered together in January. The NHS remains the largest abortion provider in the UK, but due to the financial climate, sexual health charities such as BPAS which provide not-for-profit services are increasingly taking on their work.

"It is too soon to jump to conclusions about whether this means that nationally more abortions are taking place as a whole."

The Brooks Advisory Service, which provides family planning services to under-25s, said it had yet to collate abortion figures for January. But a spokeswoman said that while there was usually increased demand for its services after Christmas, there were no reports of unusually high numbers of abortions being carried out.

The Department of Health is due to publish the national abortion figures in June.