Newcastle owner Mike Ashley put the club up for sale last month and PCP, the investment firm run by British businesswoman Amanda Staveley, was widely expected to be the main bidder for the North East team.
The source said PCP has offered different payment structures, meaning that the value of the bid was not fixed. Newcastle did not respond to a request for comment.
One offer is to pay the full amount up front and another proposes a smaller amount upfront with the rest tied to performance.
PCP Capital, which acts for investors in the Middle East and China, is best known for acting as an intermediary between Barclays and a group of Abu Dhabi investors during the 2008 financial crisis, helping the British bank avoid a government bailout.
Newcastle have been relegated twice since Ashley took charge in 2007. The club won promotion back to the Premier League last season and are currently 11th in the table.
Ashley has faced criticism for not investing more in players, and his announcement in October that the club was up for sale was welcomed by fans.
The statement, issued on Oct. 16, from Ashley's St. James' Holdings Limited, said they would be willing to allow a potential purchaser to defer "substantial" payments in order to allow the new owner the flexibility to "make meaningful investment in the club, including in its playing squad".
(Reporting by Ben Martin, writing by Simon Evans; editing by John Stonestreet)
