British regulators yesterday gave billionaire entrepreneur Mr Philip Green until August 6th to make an offer for Marks & Spencer following a month of takeover approaches to the retailer.
M&S has already rejected two approaches from Mr Green, who has made his reputation and fortune by buying up and turning around struggling chains such as BHS and Arcadia.
Last month, he revised his proposed offer to "not less than" 370p-a-share or £8.3 billion, excluding about £2 billion of debt.
The Takeover Panel said that, after discussions with both parties, it had agreed that Revival Acquisitions, Mr Green's investment vehicle, must make a bid by midday on August 6th or it would not be allowed to proceed with an offer for M&S.
M&S remains the largest clothing retailer in the UK and the fourth-largest food seller, but has seen profits and sales growth slide in recent years amid fierce competition from supermarkets and what analysts view as an ageing product range and customer base.
M&S has shaken up its management and appointed Mr Stuart Rose as chief executive in an attempt to revive the group.
The proposed takeover has already seen controversy over share purchases which has prompted an inquiry from the Financial Services Authority.
Mr Green and Mr Rose have traded barbs and were involved in an altercation outside M&S headquarters.
Mr Green is also assessing the impact of the retailer's pension liabilities, the treatment of which has become increasingly important in recent mergers.
He has said he saw the M&S pension scheme's liabilities as key to whether he makes an improved offer. Revival also urged M&S to make any funding agreements between the company and the pension scheme public.
M&S has refused to provide details of its pension liabilities, although it was understood to be encouraging the trustees to meet Mr Green.
Last Friday, Mr Green wrote to Mr David Norgrove, chairman of the trustees, a meeting. He wants greater clarity about the pension fund's liabilities.
A source close to one of the trustees expects them to meet Mr Green or his advisers.
He said they were likely to be reluctant to hand over confidential information but were anxious not to appear unnecessarily obstructive.
