Akpom has entered the final year of his contract at Middlesbrough and has been heavily linked with a move away from the club.
Boro have not made much headway in discussions over a new contract and Lens, Ajax and Sheffield United are interested in signing him.
The Championship club have already rejected Lens’ offer of £8m, but they have the money to improve their bid after selling Lois Openda for £40m earlier in the window.
It has been claimed that Sheffield United boss Paul Heckingbottom has identified Akpom as the top target to replace Iliman Ndiaye, but the Blades are not keen to spend big on him.
The newly promoted Premier League side are not keen to offer more than Lens did in their first bid for the Boro striker.
That is unlikely to be enough to convince Middlesbrough to sell the striker to the Blades in the ongoing transfer window.
Sheffield United are counting on Akpom wanting to stay in England and play in the Premier League.
Ajax are also preparing a formal offer for the striker who won the Championship Player of the Year last season.
