Republic of Ireland striker Anthony Stokes has turned down the offer of a contract extension with Celtic.
The 24-year-old signed from Hibernian in 2010 on a three-year deal, with
But manager Neil Lennon revealed: "We have already made him an offer - he has knocked that back, but negotiations will be ongoing."
It is understood Stokes is unhappy with the terms being offered.
The striker endured a frustrating season during which an ankle injury sidelined him for four and a half months.
But Stokes regained a starting place at the end of the season and finished on a high by setting up two goals in a win over former club Hibs.
"We really saw the best of him towards the end of the season," said Lennon.
"He looks physically in the best shape he has been in.
"He was such a pivotal player for us towards the end of the season and his cup final performance was absolutely fantastic.
"The opportunity is there for him to go and make a good career for himself. He is very important to me."
The former Falkirk and Sunderland forward is not the only player whose future at Celtic Park is uncertain, with and being linked with other clubs.
Asked if Wanyama would still be a Celtic player in August, Lennon said: "I certainly hope so.
"There's a lot of speculation surrounding Victor at the minute, but that's all it is, it's just speculation."
His answer was similar when asked about Hooper.
"There are no offers in and one of my priorities will be to try to keep Gary at the club," said Lennon.
"There have been no approaches for any of our players at the minute."
Lennon is due to hold talks with Celtic about , having been in the shortlist for the Everton vacancy that looks likely to be filled by Roberto Martinez.
"I have had no offers," insisted the Celtic manager. "It's nice to be linked with these things, but you take it all with a pinch of salt. It's just rumour, speculation.
"I love what I do. The size of Celtic sometimes gets underestimated, not by people here, but by people elsewhere."