British petrochemicals company Ineos is in exclusive talks with ConocoPhillips Co. (NYSE: COP) to buy North Sea oil and gas fields worth $3 billion from the U.S. energy company, the Sunday Times newspaper reported, without citing sources.

Reuters reported in May that ConocoPhillips was preparing to sell North Sea assets in order to focus on shale gas production in the U.S., and earlier this week Bloomberg said the oil major aimed to sell $3 billion of assets by the year's end.

The Sunday Times report said that Ineos, owned by Britain's richest man, Jim Ratcliffe, had paid a deposit in return for three months' exclusivity on the potential purchase.

HSBC and Citigroup had been approached to provide financing, the newspaper added.