The figure for the end of May was £179.3 billion.
Of the schemes surveyed by the PPF, some 87 per cent were experiencing a funding shortfall. In June, barely 900 of the 7,400 schemes had a surplus of funds.
Many funds have been adversely affected by a slide in the value of assets and a rise in liabilities. Deflation has also had a negative impact on pension funds, with the Retail Prices Index falling to -1.6 per cent last month.