Aleksandar Tonev will cost Celtic around £2million according to his agent.
The 23-year old Lech Poznan winger, who has attracted interest from Lazio, has also emerged as a target for the Hoops but recent performances for Bulgaria have heightened his transfer fee says his representative Gianfranco Cicchetti.
"During the winter break, several Italian clubs showed interest in him, but we could not do a deal,” he told the Daily Record.
"Then the price was £1.5m, but after his recent excellent displays and his hat-trick for Bulgaria against Malta, I would say the transfer is close to £2m.
"It's best to do a deal as soon as possible because that price could rise further if he keeps going like this.
"It's no secret Lazio are most keen. They have been watching him for over a year."