The combined deficit of the UKs defined benefit pension schemes increased to an estimated £312.1bn at the end of May 2012, the highest since records began in 2003.
Figures published by the Pension Protection Fund today reveal a 44% increase last month in the aggregate deficit of the DB schemes that are potentially eligible for PPF protection - the PPF 7800 Index. The deficit at the end of April 2012 stood at £216.8bn.
In total, at the end of May the assets of the schemes in the index were £1,030.8bn and their total liabilities were £1,343bn. This gave the index a funding ratio of 76.8%, compared to 82.6% a month earlier. There were 5,503 schemes in deficit and 929 schemes in surplus.
Joanne Segars, chief executive of the National Association of Pension Funds, said the figures reflected the 'immense pressure' private sector final salary pension funds were under.
'Cash-strapped businesses that are already struggling to keep these pensions going will have to find more assets to fill in the deficits.'
Ms Segars attributed the increase to a sharp drop in gilt yields caused by quantitative easing and the popularity of gilts among international investors seeking a 'safe harbour' from the eurozone crisis.
'That gilt fall has fuelled this record deficit, which is more a reflection of accounting rules on pensions rather than any structural weakness.'
She added: 'Pension fund assets are actually higher than 12 months ago, but liabilities have risen disproportionately. This is a volatile monthly index and it is important to remember that pension funds work over a long timeframe that helps absorb the effects of market swings.'