Sir Alan Sugar, the irascible host of the BBC show The Apprentice, has acquired a stake of almost 4 per cent in Woolworths, the embattled high street retailer.

In a Stock Exchange statement this morning, the multimillionaire founder of Amstrad confirmed that he had built a stake of 3.88 per cent through his Amsprop London vehicle.

The entrepreneur, who has become famous for the catchpharse "You're fired" on the hit TV show, is thought to have paid about £1.8 million for the holding.

Shares of Woolworths, which last month scrapped its dividend after reporting half-year losses of almost £100 million, jumped by 7 per cent in mid-morning trading, rising 0.22p to 3.36p.

The share price has fallen by more than 80 per cent over the past 12 months amid fears that it could become the next high street casualty. There have been suggestions recently that credit insurers are refusing to provide cover for suppliers.

Steve Johnson, the Woolworths chief executive, last month unveiled a turnaround strategy involving the sale of 120 stores, job cuts and the rationalisation of product lines and its internet operations.

The company, in which Baugur, the Icelandic investor, has a 10 per cent holding, recently rebuffed an offer from Iceland for its 815 stores, claiming the offer undervalued its retail operations and would leave it saddled with the pension liabilities.

Sir Alan made his name — and his fortune — turning Amstrad, his home computer business, into a household name. He sold out in 2007 to BSkyB, in which News Corporation, parent company of The Times. has a 39.1 per cent stake, and has since invested heavily in commercial property.

Analysts suggested that the purchase of a stake in Woolworths was the latest sign of wealthy individuals dipping a toe back into the market to take advantage of sharply reduced share values.

This week, Joe Lewis, a fellow Londoner who is now a tax exile in the Bahamas, took advantage of the fallout from Iceland’s financial meltdown to buy a 25 per cent stake in Mitchells & Butlers, the pub operator, from Robert Tchenguiz.

A spokesman for Sir Alan declined to comment, claming that despite his new-found fame as a TV star he rarely commented on his business interests.

Separately, Woolworths announced the disposal of the leases on up to nine stores to Tesco for up to £9 million.

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