German utility RWE is reported to have made an indicative all-cash offer for British Energy of close to 700p a share.

The said deal, that could value the UK's nuclear operator at up to £11 billion, sent shares up 30p, or 4% in early trade to 731 pence.

RWE, which reportedly made the offer several weeks ago, has, according to the reports, been granted access to British Energy's data room and is carrying out due diligence.

The offer was made before British Energy confirmed on 17 March that it was in talks that could lead to a full takeover. British Energy has not yet triggered a formal auction of the company and is still considering whether to sell to one bidder or a consortium.