By Jonathan Davies

Royal Dutch Shell says it has agreed to buy oil and gas exploration firm BG Group in a deal worth £47 billion.

Shell has offered a cash plus shares deal in which BG Group's shareholders will receive 50% more than its share price on 7 April.

BG Group's shares surged 42% to 1,293.5p when the London Stock Exchange opened on Wednesday.

Shell will also give BG's shareholders the option of choosing the ratio of how much cash and shares they receive.

BG Group has a market capitalisation of around £31bn, and with Shell's standing at around £177bn, the combined company could be worth more than £200bn.

The deal is expected to save the combined company around $2.5bn a year, with 25% added to Shell's oil and gas reserves and 20% to its production capacity.