The "double whammy" of Christmas and the credit crunch will make this week one of the busiest ever for divorce lawyers, experts said today.

One in four people say their relationship is under strain because of money problems, according to a new survey.

Ironically, 11% of those polled say they are being forced to stay in a failing relationship because the financial crisis means they cannot afford to leave.

Researchers for online advice centre InsideDivorce.com found almost two million couples in Britain were suffering marital difficulties and 1.3 million people were considering splitting up.

The traditional New Year rush to end marriages after the stress of Christmas means divorce lawyers brand today D-Day, or Divorce Day, kick-starting their busiest week of the year.

And with 17% of divorced men blaming financial problems for the end of their marriage, the credit crunch is putting extra pressure on relationships in trouble.

Leading divorce lawyer James Stewart from Manches LLP said: "A stressful Christmas is already often the final straw for marriages in trouble.

"The double whammy of Christmas and the credit crunch will make the first full week of January one of the busiest ever."

Relate, the UK's largest provider of relationship support, said it had a 59% surge in the number of calls to its centres over the festive period.

TakeLegalAdvice.com, a website which matches consumers with lawyers, also saw enquiries about relationship difficulties soar over Christmas, up a third compared to the same period last year.

"Christmas can be a nightmare for couples who are already experiencing marital problems," said Derek Bedlow, the site's managing editor.

"Many think about divorce but the added pressures brought about by the downturn may be the straw that breaks the camel's back."

Yet divorce creates its own financial problems, with one in three divorcees falling off the property ladder or having to downsize as a result.

Two in five reported increased levels of happiness following their split - though just 29% of men said they were happier, compared with 49% of women.

The survey's revelations about British relationships included the finding that 17% of marriages are entirely sexless - a potential trigger of infidelity, cited by two in five (38%) people as key factor for divorce.

The other common reasons for splits were abuse (34%) and boredom, cited by almost one in three (29%) people.

The survey also revealed that prenuptial agreements are still unusual, used by just 2% of people who were divorced or married.

Nearly a third (28%) of those who had no agreement said in hindsight they regretted the decision not to arrange finances before marriage.

The researchers surveyed 700 married, divorced, separated and cohabiting adults across the UK.