Northumbrian Water has received a takeover proposal from a company owned by Hong Kong billionaire Li Ka-shing.
The indicative proposal related to a possible cash offer from Cheung Kong Infrastructure Holdings, the water company said in a short statement.
CKI had said earlier this week it is in the preliminary stages of assessing a potential cash offer for Northumbrian.
Northumbrian shares have risen nearly nine per cent since CKI said it is considering a bid. They closed at 415.6 pence on Thursday, valuing the company at £2.1bn.
Analysts have said CKI could end up paying between 450 to 500 pence per share for Northumbrian.
Britain, a country open to foreign ownership of its infrastructure assets, has proved a popular investment destination for the octogenarian Li, Hong Kong's richest man, who has bought into regulated UK utility assets in the past.
CKI has already invested in two unlisted British water companies. It owns Cambridge Water and has a 4.75 per cent stake in Southern Water, according to CKI's website.
City A.M. Reporter