At a meeting in London, 99% of Kingfisher shareholders voted in favour of the offer, as well as backing a £2bn rights issue to help pay for the deal.

Kingfisher plans to bid 67 euros a share to buy the 45% of Castorama that it does not already own as it looks to strengthen its DIY operations, which include the British B&Q chain.

The bid has been opposed by a group of five founding Castorama shareholders, who say they believe the offer is too low.

Decision in July

Kingfisher, which also owns electricals chain Comet, bought 55% of Castorama in 1998 to create Europe's largest DIY group, but it did not take overall voting control.

The bid will now be assessed independently by investment bank Rothschild, which will decide if the offer is fair.

It is expected to give its decision by 7 July.

If it decides the offer is too low, the bank will set a minimum price - with Kingfisher being given three months to decide whether to up its offer, which would require shareholders to approve additional funding.

The company's stock was down 1.5% at 352p in morning dealings.