Manchester United bidder Sheikh Jassim bin Hamad Alhs already warned the Premier League club that he is prepared to walk away from takeover talks as the sale process drags on.
Reports last week claimed that United are negotiating exclusivity with Sheikh Jassim, who submitted a fifth and final bid for the club earlier this month.
Speculation is growing that the Qatari banker has been successful with his latest offer, which is understood to be worth around $6.5bn (£5.2bn) – with an additional $1bn (around £800m) of investment in the club also pledged.
However, the BBC claim that exclusivity had not yet been granted by Raine - the banking group handling the sale on behalf of the owners, the Glazers - and that talks are continuing with interested parties.
Britain's richest man Sir Jim Ratcliffe has also submitted several offers for the Premier League club through his INEOS Group.
Unlike Sheikh Jassim, who is attempting a full takeover, INEOS are seeking a controlling stake over 50 per cent which could allow the Glazer family to retain some involvement in the club.
It is now more than 200 days since the Glazers first announced they were exploring 'strategic alternatives' for the club, effectively putting it up for sale.
There are growing concerns over the length of the sale process and its potential impact on United's summer transfer business, with the domestic window now open for English clubs.
And Sheikh Jassim has previously shown signs of running out of patience with Raine and the Glazers.
According to a report by the Financial Times (via Manchester Evening News), Sheikh Jassim 'threatened to walk away' from the whole takeover process after tabling his fifth bid for United last week.
His final offer is believed to have been made with a 'take-it-or-leave-it' approach, refusing to re-enter negotiations until a preferred bidder had been named.
While he is now considered as the leading candidate to buy United, Sheikh Jassim has shown signs that he could be prepared to walk away if there continues to be a lack of progress in the sale.
