KRIS Commons could leave Celtic over a failure to agree the length of contract being offered by the club.

Ronny Deila, the manager, strongly hinted yesterday that Celtic are wary about offering a long-term deal to the 31-year-old and that the length of contract, rather than the financial package on offer, is the reason for months of stalling on a new deal. It is understood that Commons wants the security of a reasonably lengthy contract but Deila said there was "danger" in a club committing to a long deal on an older player.

Commons is out of contract at the end of the season and is free to speak to other clubs from January 1, with Crystal Palace and Neil Lennon's Bolton linked with him recently.

Deila does want him to stay but yesterday he appeared to endorse the club's reluctance to offer longer contracts to older players. Scott Brown last week signed a new deal which tied him to Celtic until 2018 but the captain is 29, two years younger than Commons.

Talks between Commons and Celtic have been dragging on for most of this year. "I don't think the money is a problem," said Deila, ahead of tonight's Europa League Group D game against Red Bull Salzburg at Parkhead. "If we want to do it, we can do it. It's more about policy than the sums of money. If the demands for money are unbelievably high then the club could be ruined.

"So it's not the cash that's the problem. It's if you want double the next paid player at Celtic, that's a problem. Thankfully we have not had any problems like that so far."

But when asked if the length of deal was an issue with Commons, Deila said: "That's something we are thinking a lot of, of course. We have to do the right things for the club and provide for the interests of the club.

"The length is something we always have to look at because when you get older a long contract it is a danger. It's good for the player. If we keep the player fit all the time and motivated it's no problem.

"But you never know what will happen in a year. If an older player has a long contract then injury could hit and you have used a lot of money you cannot get back. But when he is at the top of his game as a player there is no problem. You know that he has a high impact on Celtic."

Deila's intention to make Celtic a quick, mobile team, capable of fast attacking, has led to speculation about whether Commons truly fits with that style. Commons is neither quick nor mobile, although his technique, creativity, imagination and goalscoring have made him invaluable. "I think international football now needs 11 players who have to run hard," said Deila. "Kris has skills which are unbelievably important.

"He is very creative, he is a goalscorer and has good relations with the players around him. His defence play is something he has to develop. But he is starting to work harder and doing his job better. As far I've been told [Commons' representatives] have to come back to us now with an answer to what we have offered."

John Guidetti's agents are expected to meet with Celtic in the next 48 hours to discuss whether the on-loan striker could stay at Parkhead beyond the end of this season when he, too, will be a free agent.

Aleksandar Tonev's appeal over his seven-game suspension for a racist comment is to be heard by the SFA on December 4.