Harris, who in the past also brokered the sales of Aston Villa, West Ham and Manchester City, said due diligence has already been done and the party he was representing has not been mentioned publicly before.
"The overseas buyer we represent has completed due diligence. A huge amount of work has been done," Harris said. "It is none of the groups mentioned in the press. The ball is now in our client's court to make an offer.
"I do not think the deal will be done before the transfer window closes this month but the next pressure point is October when some of the RBS loan of £237million has to be repaid. It may happen then. But in the present climate these things are impossible to predict."
Hong Kong businessman Kenny Huang withdrew from the bidding to takeover the club over the weekend. Other candidates in the mix include Syrian businessman Yahya Kirdi, who represents a group of investors from the Middle East and Canada, New York-based private equity firm The Rhone Group and Kuwaiti investment group the Al Kharafi family.
