Britain's biggest companies may need to put aside up to £150 billion to repair the damage inflicted on their pension schemes by huge falls in share prices.

Experts suggested yesterday that the vast majority of company schemes would need more capital if they are to guarantee to meet their obligations to staff who have yet to retire.

The financial crisis and fears of an imminent recession have sent the blue-chip shares tumbling by more than 23 per cent in three months.

Edmund Truell, a pensions expert, said that sliding share prices meant that most trustees would be considering whether to ask companies for more money to top up their schemes. He said that 85 per cent of major company schemes required additional cash. The request for more money from trustees, who are responsible for safeguarding pensioners' rights, will add to pressure on companies that are already struggling with the economic downturn.

Shares in the FTSE 100 index have slumped from a high of 6,677 this time last year, a fall of 36 per cent, blowing huge holes in pension funds. Despite efforts by funds for more reliable returns over the past four years, experts reckon that 53 per cent of pension scheme assets remain invested in the stock market. As well as the decline in share prices, the falling price of office and industrial property, in which many pension funds were heavily invested, has also undermined schemes.

City analysts predicted yesterday that several other well-known companies would come under pressure to put cash into their funds. According to Morgan Stanley, the investment bank, companies likely to be asked to shore up their pension funds include Trinity Mirror, the media group, Woolworths and Aga Rangemaster, the oven-maker.

Tom McPhail, head of pensions research at Hargreaves Lansdown, the stockbroker, said: “There are going to be some tense negotiations between companies and their pension schemes. In some cases it will happen very quickly. In others it will take months to resolve.”

Jerome Melcer, a partner at Lane, Clark & Peacock, the pensions consultant, said that trustees faced a dilemma balancing their responsibility to safeguard the interests of pensioners, against destabilising companies by asking for too much money.

“Trustees really want to keep the patient alive,” he said.

Mr Truell said that bank lenders were increasingly concerned about the exposure of companies to their pension schemes. If a company fails, administrators are normally obliged by law to pay pensioners ahead of bank lenders. He said that, in some cases, banks were threatening to withhold funds until pensions shortfalls were made good.

The falls in the stock market are also threatening to undermine pension benefits generally, making it more likely that companies will have to close their pension schemes to new members over the coming months.

In recent years many companies have ended their final-salary pension schemes, which pay a pension based on salary and service, in favour of less generous money purchase plans, which still offer a payout linked to the stock market but leave the investment risk with staff.

The current malaise threatens to sound the death knell on those final-salary schemes that remain. According to the National Association of Pension Funds, fewer than 30 per cent of final-salary pension schemes remain open to existing employees.

Express Newspapers revealed plans yesterday to shut its final-salary pension scheme to existing members to save cash. The newspaper group wrote to staff detailing the plan yesterday.

The Government set up the Pension Protection Fund in 2005 to take control of pension schemes in the event of a company collapse. It said yesterday that it was preparing for an increase in insolvencies.

Yesterday the Pensions Regulator said that it was looking at new powers that would give it the right to force companies to top up pension schemes.

The regulator plans to act against companies that put their own interests ahead of their pension schemes. Under the proposals, which will be incorporated into the forthcoming Pensions Bill, the regulator will be able to pursue companies for up to six years and would not have to prove that companies meant to harm the fund.

Under the Pension Protection Fund, members receive full compensation if they have reached retirement age at the time that the employer went bust. Compensation is subject to an upper limit, which is recalculated every year. Between April this year and next March the maximum payout at age 65 is £30,856.35 a year. Compensation payments rise in line with inflation, subject to a maximum of 2.5 per cent a year.

There are 57 schemes and 18,957 people in the protection fund. Its chief executive, Partha Dasgupta, said recently: “We have seen no significant increase in claims.”

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