Trinity Mirror rejected City concerns that it may have to make substantial payments to help to prop up its £1.5 billion pension fund.

The under-pressure newspaper group issued a statement to The Times last night saying that it had no liquidity issues with its pension fund.

However, there are concerns that the size of the fund relative to Trinity's diminished market value means that a large deficit could open up suddenly.

Financial worries also plague Trinity Mirror's rivals, with analysts saying that Johnston Press may not have raised enough cash in a recent rights issue to avoid problems with its banking covenants should the existing advertising downturn get worse.

A top ten shareholder contacted by The Times, who asked not to be named, said that Trinity Mirror should consider offloading its pension fund as it was a potential risk. The publisher said that it has no plans to do so.

Lorna Tilbian, an analyst with Numis Securities, said: “The worry is that these things can change so quickly, when the funds are next valued.

The company has £210 million in undrawn borrowings, but it will also need to think about dividends, invest in the business and retain capital in the business.”

Worries about the potential risk have weighed on the shares after Monday's sharp profits warning, which followed a collapse in advertising at the company's national and regional titles in May and June.

A formal valuation of one of the group's largest funds is due by the end of the year.

The company's pension fund is in deficit by £125 million, according to the last set of full-year accounts, but the company's market value has fallen to £236 million after the profits warning. Trinity Mirror's shares are down 83percent in the past 12 months.

Robert Maxwell, who bought the Mirror Group in the 1984 and owned it until his death in 1991, plundered the pension funds. Although those issues are now resolved and do not contribute to the current deficit, the memories of Maxwell gives concerns about the health of the current pension scheme an extra resonance.

However, Trinity Mirror insiders said that while the value of the pension fund's assets will fall when global stock markets tumble, the decline will be offset by an increase in the discount rate used to benchmark the scheme's liabilities.

The discount rate reflects the value of AA bonds.

A spokesman said: “We continue to fund our deficit in accordance with the payment schedule already agreed with the trustees of the various pension funds.”

Shares in rival newspaper publisher Johnston Press continued to fall this week as the City expects it to follow Trinity Mirror with a profit warning. Its fell 4p, or 11 per cent, to 31.5p, capping a fall of 93 per cent over the past year.

Johnston secured its balance sheet with a £212 million fundraising, but with debts expected to end the year at £450 million, pressure remains.

Numis Securities calculates, on its existing forecasts, that borrowings will be 2.7 times underlying earnings. Johnston has to keep its debt lower than four times to satisfy its banks.

“If there was further downside in the company's trading, that could make it difficult,” Ms Tilbian said.

On the broker's analysis, in the last recession in the early 1990s, classified advertising fell by 39 per cent and display by 11 per cent over the cycle.

However, in the course of the year so far, some sectors of classified advertising - property and motors - have fallen by about 20per cent. Trinity Mirror said that all advertising fell by 12.6 per cent in May and June.

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