Energy utility RWE AG (RWE.XE) is closing in on the planned sale of its U.K.-based nuclear energy joint venture with peer E.ON AG (EOAN.XE), a company spokeswoman said Thursday.

The utilities are in "very advanced" talks over the sale of the Horizon Nuclear Power joint venture, the spokeswoman said, adding that an announcement could be made in coming days.

The comments come after a German daily newspaper reported earlier Thursday that RWE and E.ON are set to sell the nuclear joint venture to a consortium led by
Japan 's Hitachi Ltd (6501.TO).

The RWE spokeswoman and a spokesman for E.ON declined to comment on details.

The two German utilities formed Horizon Nuclear Power in January 2009, looking to invest around 15 billion pounds ($24 billion) to build at least 6 gigawatt of nuclear power generation capacity in the U.K.