Rival bidders for Manchester United have been invited to submit a third offer by the end of April, according to reports.

Qatari banker Sheikh Jassim Bin Hamad Bin Jassim Bin Jaber Al Thani and British billionaire Jim Ratcliffe both submitted a second bid for the Premier League club last month.

Several offers are understood to have been received in recent weeks but Sheikh Jassim and Ratcliffe remain the front runners to buy United should the Glazers family give up control of the club they bought in 2005 for £790 million ($980 million).

United's unpopular owners announced in November they were conducting a strategic review, with the sale of the club one option being considered.

The Qatari group has reportedly made an offer of about £5 billion for 100% ownership of the club while Ratcliffe, a boyhood United fan, wants to buy the combined Glazer shareholding of 69%.

The Americans' asking price is believed to be around $6 billion -- a figure that would make the 20-time English champions the most expensive sports club in history.

Finnish entrepreneur Thomas Zilliacus last month entered the race and US hedge fund Elliott Investment Management is understood to have made a bid for a minority stake.

It is noteworthy that the Glazers have angered many United supporters by burdening the club with huge debts over the past 18 years.

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