Philip Yea abruptly quit as chief executive of 3i today as Britain's oldest private equity group reported a £682 million fall in the value of its top 50 investments.

Mr Yea's departure, for which he is expected to receive about £790,000 in compensation for loss of office, was announced after it emerged that 3i was facing a possible creditor takeover at VNU Business Media Europe, the Dutch media business that it bought at the height of the buyout boom.

VNU, which 3i bought for €320 million in 2006, is believed to be close to breaking its banking covenants.

Mr Yea, who had run the business since July 2004, is to be succeeded by Michael Queen, who has run 3i's infrastructure fund since 2007.

Baroness Hogg, the chairman of 3i, said that Mr Yea was "stepping down to assist the transition to the next generation of leadership" and thanked him for his "great contribution".

However, the suddenness of the change in helmsman is likely to take the City by surprise.

Philip Middleton, of Bank of America/Merrill Lynch, said that the change was "likely to cause some short-term uncertainty about strategy. We would expect that it will suggest a move towards battening down the hatches further, as the company seeks to get to grips with its balance sheet."

The shares fell by 9 per cent in early trading but by mid-morning rallied to 249p, down 2 per cent.

Mr Queen, speaking to The Times, refused to rule out a rights issue given the unprecedented market conditions.

He said: "I don't know whether we are at the bottom of the downturn or even close to it."

However, he added: "As we stand at the moment, we do not need additional capital."

The group had liquidity of £839 million after realising £345 million of investments in the final quarter of 2008.

Analysts were unaware that a management change was in the offing, although there has been growing concern about the group's prospects.

Today 3i took the unusual step "in recognition of the volatility of markets" of publishing a valuation of its top 50 companies, revealing they had fallen in value by 21 per cent to £3.6 billion as at December 31, 2008.

Mr Queen was finance director of 3i in the eight years to 2005 before moving into operating roles at the group.

No external search was made for the new chief executive, he said, although there was a proper internal process.

Mr Yea, a former finance director of Diageo, the drinks group, was poached by 3i at the last moment when he had been lined up to head British Land.

That post was then filled by Stephen Hester, who left two months ago to head Royal Bank of Scotland.

Mr Yea, 54, said that it had been a privilege to lead 3i.

In its trading statement 3i disclosed that it had banked £345 million from asset disposals and made new investments of £173 million in the three months to December. Net debt was £2.1 billion.

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