Four private equity groups are understood to be looking afresh at NTL, whose shares have fallen 20 per cent over the past four months as it struggles to demonstrate the benefits of its recent £3.4 billion takeover of Telewest.

The bid approach, which is understood to be dependent on NTL’s share price falling below its current level of $24.42, would represent one of the largest private equity buyouts.

The renewed interest in NTL comes as key investors in the cable group prepare to write to Steve Burch, its chief executive, to make a formal complaint about the board’s out-of-hand rejection of a private equity approach late last year. NTL said that the approach undervalued the group and maintained that it could create better value for shareholders as an independent company. The tie-up with Telewest, it said, would trigger significant savings and help the group to forge ahead of players such as BT.

Since then, however, NTL shares, which hit a peak of $29 on Wall Street in April, are back at the same level as when the Telewest deal was completed. The shares closed yesterday at $24.42.

The complaint letter, backed by at least two key NTL investors, will demand that the board seriously consider any future offers for the cable group. It will also ask why last year’s $32-a-share approach — which represented a 40 per cent premium to the company’s share price — was not entertained.

A poor set of second-quarter results last week, in which NTL unveiled a sharp drop in customers and gave warning of further poor performance, also rattled investors. It is unclear whether the private equity firms currently circling NTL are the same ones that approached the cable group last year. Investors are aware, however, that any fresh approach is likely to be pitched at a much lower price than last year’s approach, in light of the group’s performance and the increasingly competitive UK market.

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