Celtic managing director Fergus McCann last night launched an astonishing attack on the conduct of Marko Viduka and cast doubt on ever seeing him play for the Parkhead club.

McCann, speaking after last night's 2-1 loss at Hearts, convened a special news conference in response to Viduka's statement earlier yesterday that he planned to return when he has regained his mental equilibrium and match fitness.

A bemused McCann expressed hurt at Viduka's departure from Celtic, which he still believes to be permanent, and at first put his thoughts into a fresh statement.

It read: "The club is now most concerned about certain aspects of the transaction regarding Marko Viduka.

"We will be seeking clarification over the next few days from various parties, including Croatia Zagreb, in particular in relation to the disposition of the transfer fee agreed some time ago.

"The comments from the player released today through IMG (agents International Management Group) are not consistent with his actions and statements over the past two days."

When asked whether Zagreb would be paid their £3 million, McCann said: "We will want to get several questions answered and clarified in the next few days."

When asked about the prospect of legal action, McCann added: "We are getting our position clarified by legal advisers as we speak and we will be giving more information in time."

McCann voiced his fears for the future based on the fact that Viduka has so far turned his back on every effort made by Celtic to understand the root of his problems.

"Marko Viduka had been playing football at the highest level until recently and there was no indication either from the player, Zagreb or IMG of any psychological problems," he said.

"He was offered medical counselling, his parents to be flown to Glasgow from Australia, a change of hotel, a furnished apartment, a car and a driver, an extended Christmas break and a member of Celtic staff with him at all times.

"These offers were all rejected.

Marko advised that he was depressed, unhappy, didn't want to play football. He had difficulties in Zagreb but would not elaborate upon them."

Yet Viduka earlier yesterday vowed to return to active service for Celtic as soon as he has regained his mental and physical fitness.

He said in a statement: "It was only after I arrived in Glasgow last week that I started to realise how much I had been affected by events in Zagreb over the last few months where I had been under enormous personal pressure.

"I would just ask everyone to be patient while I get back to full fitness as soon as possible."