The increased offer of 270p per share plus 2p in special dividend represents an increase of approximately £400m to Fortress’ original offer value.
In a statement, the supermarket stated that the offer was in the “best interests” of its shareholders as a whole and considered the terms of the increased Fortress offer to be “fair and reasonable”.
Silcherster, the largest shareholder at Morrisons, had previously claimed it was “not inclined” to support the previous £6.3bn offer, which had been accepted by the company’s board.
Morrisons, which is the UK’s fourth-largest grocer, had also previously rejected an £5.5bn offer from Clayton, Dubilier and Rice (CD&R), which valued Morrisons at 230p per share.
Despite this, there were reports that CD&R was planning to submit a new higher offer.
Under UK takeover rules, the firm has until 9 August to bring a new offer to the table.
It is understood that all shareholders in Morrisons are due to vote on the new and improved takeover bid on 16 August – with the group requiring a 75% approval to pass.
Morrisons, which is headed by David Potts, has almost 500 shops and more than 110,000 staff.