BT is being examined as a potential bid target by a number of global private equity firms in a move that could value the telecoms group at a minimum of £20 billion, The Times has learnt.

One senior adviser specialising in telecoms for a leading venture capitalist told The Times that his firm had been running a slide rule over BT, but that it had encountered obstacles to making a bid that included the financial structure of such a large deal and the company’s pension fund deficit.

It is also understood that a number of other private equity firms are also weighing up bids for BT.

Sources told The Times that any approach to BT would require a consortium of several private equity firms, because most venture capitalists can only commit 10 per cent of any one fund to a specific deal.

The telecoms group is attractive to venture capitalists because its stable cashflows could be used to pay off the more than £10 billion of debt that would be needed to fund the leveraged buyout.

Potential private equity bidders could also sell other BT assets, such as its network, to help to fund the deal, sources added.

Any deal would be several times larger than the biggest buyout of a British company so far — Texas Pacific’s £2.5 billion takeover of Allied Domecq’s pub estate in 1999.

Analysts said that a buyout of this size was possible after the dramatic growth of the private equity industry in the past five years. However, it would push even the best-financed consortiums to the limit and would occur only if they felt the business offered tremendous growth potential, requiring an equity cheque of up to £12 billion.

The group’s pension deficit, which totalled £3.8 billion under FRS17 accounting standards at the end of last March, and the ever more evident uncertainity of the telecoms environment would also be considerations.

The interest in BT came as it emerged that private equity firms raised enough money last year to buy 43 per cent of the FTSE 100 by value. Private equity funds raised €248 billion in 2005, which is enough to fund leveraged buyouts of €1 trillion (£680 billion), since two thirds of each deal is typically financed by debt, according to Deloitte.

Oliver Tant, global head of advisory services at KPMG, said: “It’s a matter of when, not if, a private equity consortium will take over a FTSE 100 company and I expect this to happen in the next 12 months. With the size of funds being raised for private equity at the moment, there is the real prospect that a club deal could put together a bid of over £20 billion.”

This means that only the 19 biggest companies in the FTSE 100 — BT is 22nd — are beyond the reach of private equity firms.

Iain Scouller, a private equity analyst for UBS, said: “There is a lot of concern that too much money is now chasing too few deals in private equity. But if they start taking over much bigger companies, as I suspect they will, this will be less of a problem.”