Pensions shortfalls at the UK's largest companies have dropped sharply in recent weeks, according to new surveys, pointing to increased volatility in the accounting standards used to value them amid criticism of those standards by an influential UK investor group.

The total deficit in the FTSE 100 is at a five-year low of £21bn (€31bn), according to analysis by accountants Deloitte. The accountants said a quarter of firms now have pension schemes in surplus.