Everton have reportedly offered Celtic around £12m up front to sign Alistair Johnston.
According to the Daily Record, the Premier League club have submitted an initial bid of £12m plus add-ons for the Canadian right-back.
However, Celtic are reportedly pushing for an increased fee as Johnston is close to a move.
It's reported the total deal would be worth up to £15m for Johnston, who has three years left on his Parkhead deal.
Johnston is thought to be keen on a switch to the Premier League and has made this clear to Celtic officials during the summer transfer window.
But no deal has yet been reached to sell Johnston with Celtic holding out for an improved package.
According to reports, though, it's expected a deal is likely to be "thrashed out" with Johnston moving on from Celtic this summer.
"I've spoken to him on the back of the interest," Celtic boss Martin O'Neill said when quizzed on Everton's interest in Johnston. "Again, it was one of those where Alistair is perfectly happy here at the football club.
"But like anything else, your head can get turned very quickly, particularly if it's a really good club.
"He wouldn't leave here for a second-class Premier League club, if there is such a thing, but if a big, big club comes in, it's something you would have to look at. And I think it's only natural as well. If I were a player, I'd be exactly the same."
