ONE of the world's richest men is considering making a bid to buy Durham City's largest private sector employer.

Cheung Kong Infrastructure Holdings (CKI), the investment vehicle of Chinese billionaire Li Ka-shing, said last night that it was considering a cash offer for Northumbrian Water Group.

The utility firm, based at Pity Me, near Durham City, employs 936 at its head office and 2884 in total.

Hong Kong based CKI released a statement to the London Stock Exchange after speculation regarding a possible offer for the plc.

It said: "CKI is in the preliminary stages of assessing a potential cash offer for Northumbrian Water.

"There can be no certainty that an offer will ultimately be forthcoming.

"A further announcement will be made when appropriate."

Northumbrian Water declined to comment last night, as is its usual practice regarding any speculation about possible takeovers.

Earlier this month Northumbrian, which also owns Essex & Suffolk Water, announced a leap in annual profits to £181m from £170.2m.

Shares in Northumbrian rose following yesterday's announcement and the firm, with 4.4m customers in the North-East alone, is valued at around £2bn.

Li Ka-shing, who has estimated personal fortune of $26bn, is the world's eleventh richest person and is known as Superman in Hong Kong because of his business prowess.

He already has stakes in a number of UK utility companies, including Southern Water, Cambridge Water and Northern Gas Networks.

In July last year he headed a consortium which bought the UK electricity distribution networks of French energy firm EDF for £5.8bn ($9.1bn).

The 83- year-old left school at 12 and had to provide for his family at the age of 14 following his father's premature death.

By 1950 he had started his own company, Cheung Kong Industries, which he developed into a leading real estate investment firm, that was listed on the Hong Kong Stock Exchange in 1972.

He is known for his philanthropic work, having donated more than $1bn to good causes and for not flaunting his wealth, wearing a $50 watch in the 1990s.

The Cheung Kong group's businesses include property development, hotels, telecommunications, e-commerce, finance and investments, retail, ports, energy, media, and biotechnology.

He was named Entrepreneur of the Millennium by The Times at the turn of the century.