MARKS & Spencer came under renewed pressure last night as retail tycoon Philip Green gained the backing of a major shareholder for his planned takeover.

Analysts expect the latest, and final, £9.1bn offer from Mr Green to be successful.

In a statement to the Stock Exchange yesterday, billionaire Mr Green said he was planning to make a final offer of 400p per share for M&S.

The proposal will be delivered to shareholders ahead of the August 6 deadline set by the Takeover Panel on Tuesday.

Mr Green has increased the pressure on M&S by revealing the new offer has the support of its biggest shareholder.

Brandes, based in the US, has agreed to sell its 11.7 per cent stake in M&S if Mr Green makes a formal bid.

Anthony Platts, of Tees Valley investment managers Wise Speke, said: "Philip Green's revised proposal offering 400p per share for M&S really puts the cat among the pigeons. This offer will be difficult for the M&S board to reject without reference to shareholders.

"Given that the shares were trading at around 280p prior to Philip Green first showing his hand, 400p may be too good to turn down. Philip Green already has the support of the largest shareholder, US-based pension fund Brandes, which has an 11.7 per cent holding.

"The stakes have clearly been raised and in this ping-pong battle of wits, the ball is now firmly back in the court of the Marks & Spencer board."

The deal still depends on the support of the M&S board and other conditions, including due diligence.

M&S has previously rejected two approaches from Mr Green, which it said significantly undervalued the group and its prospects.

The latest offer of 400p a share is an improvement on the entrepreneur's previous proposal to pay shareholders at least 370p for each M&S share.

Investors would also be able to accept a lower sum and take a 30 per cent stake in Revival Acquisitions, the company formed to make the bid for M&S, which Mr Green intends to float on the stock market.

City stockbrokers Seymour Pierce said the offer was too high for M&S to dismiss summarily and it should attract the support of other investors.

News of the improved offer drove shares in the retailer more than six per cent higher in early trading.

M&S chief executive Stuart Rose is due to outline his vision for improving the trading performance of the retailer on Monday.

This is expected to include savings from the supply chain, a revaluation of M&S property and initiatives to increase sales.