Final salary pension schemes have gone back into the red and now face a deficit of £24.1bn, according to figures released by the Pension Protection Fund.

The data revealed a decline from a surplus of £8.3bn in June and from £83.3bn in July 2007.

"Over the past year the negative impact of equities on scheme assets, combined with falling bond yields, have led to an overall worsening of the funding position," the PPF report said.

"Lower bond yields resulted in an 8.6% increase in aggregate liabilities, while weaker equities have reduced assets by 7.4%," it added.

The figures will add to the pressure for employers to top up the schemes with their own money.