Pension scheme deficits held by Scottish companies listed on the FTSE 100 and FTSE 250 grew by £1.8bn between the end of June and July 16, according to analysis by Buck Consultants.

Buck said the increase in was caused by the estimated value of assets dropping over that period on the back of an 8% fall in the UK stock market.

Deficits this month have grown faster than they did during the entire month of June as markets move into bear territory. Based on a number of actuarial assumptions, Buck said there was a £1.3bn growth in deficits last month.

Since the start of the year, there has been a jump of £2.7bn in deficits resulting from an estimated decrease in asset values of more than 10% because of the credit crunch. This was only partly offset by a fall in liabilities of almost 5% as a result of an increase in corporate bond yields from 5.9% to 6.5%.

Buck said the financial position of pension schemes could change daily as there is still huge market volatility.

The situation looks even worse for schemes when improvements in life expectancy are taken into account. According to Buck, the overall liabilities of schemes would increase by around 3% if members were to live one year longer than the assumptions made by companies in their latest published accounts. This would add approximately £1.3bn to the liabilities of the companies covered by Buck's analysis.

Fraser Smart, a director with Buck Consultants, said: "I would tell those looking to retire in the near future not to worry. But looking to the longer-term, more defined benefit schemes are likely to close to future accruals and will struggle to keep going."