The combined deficit of the UKs defined benefit pension schemes increased to £256.6bn last month, according to figures published by the Pension Protection Fund today.
The estimated figure for the end of April represents a £20bn increase from the £236.6bn deficit recorded at the end of March for the 6,316 schemes that are currently eligible for entry to the Pension Protection Fund.
According to the PPF's figures, the total assets of the schemes were worth £1,130bn and their total liabilities were worth £1,387bn, giving a funding ratio of 81.5%, compared to the 82.6% estimated at the end of March.
In total, 5,142 of the schemes in the PPF 'universe' were in deficit, and 1,174 schemes were in surplus.
Separate figures published yesterday by the consultancy Mercer put the combined pension scheme deficit of the UK's 350 leading companies, the FTSE 350, at £108bn at the end of last month.
Mercer's estimates, which are based on the IAS19 accounting measure, revealed a £19bn increase in the deficits of FTSE350 firms last month, up from £89bn at the end of March. At the end of 2012, the company's Pension risk survey estimated the combined deficit stood at £72bn.
Last month's increase in deficits was fuelled by a £24bn in scheme liabilities - up from £641bn to £665bn - caused by a significant fall in high quality corporate bond yields.
Ali Tayyebi, Mercer's head of DB risk in the UK, said: 'The equity markets recovered well from their dip early in the month and asset values increased by around £5bn over April. It will therefore be a surprise and disappointment to many that both liability values and deficits still managed to reach highs not seen for several years.
'The key driver was the fall in high quality corporate bond yields, which have closely tracked the sharp falls in real gilt yields in late March / early April, so that the difference between the yield on these corporate bonds and market implied price inflation is now only just over 1% per annum.'
He added: 'The environment is proving particularly frustrating for many schemes who will have experienced significant improvements in their asset values but who feel that de-risking into gilts does not look particularly attractive at current prices.'