CURTIS Nelson will only leave Oxford United for a “substantial” fee next month – despite heading into the last six months of his contract.

The centre back, who cost the U’s £280,000 via a tribunal following his move from Plymouth Argyle in 2016, is likely to attract interest during the January transfer window.

Nelson was stripped of the captaincy in September over a lack of progress in talks on a new contract.

It remains unresolved, although Robinson believes the best outcome would be to agree a fresh deal which contains a release clause if a bid at a specified level was submitted.

Otherwise the U’s head coach’s stance from the summer has not changed – he would rather players left for free at the end of their deals rather than forcing the club to take a reduced fee early.

“I would let it run down,” he said.

“But every player has a price tag, it’s as simple as that.

“At this level of English football you can’t ever say not one player will be sold.

“There’s a substantial price tag on Curtis Nelson’s head and we’re not going to budge from that.

“With someone who is a talented player, there will always be people who will ask that question.

“I’d like to think that it will be done in a correct way, if it’s done. We’ll have to wait and see.”

Robinson was unaware of rumoured interest from Sunderland, but there appears little evidence negotiations over a new deal will bear fruit, although there is hope a compromise can be reached.

The United boss said: “We sit down with him and his agent to try to make something happen and maybe give him the opportunity to have a buy-out clause in his contract.

“(That way) we don’t hold him to ransom in regards to a ridiculously high transfer fee, which is what we’ll hold him to in this window.”

While Nelson becoming a free agent next summer would put him in the driving seat for contract talks, it only applies if he was fit.

The centre back missed five months of last season with an Achilles injury and Robinson highlighted the risks.

He said: “Players at this level earn fantastic money, but it’s not the money that lasts a lifetime.

“So you’re gambling. That’s not just Nelse, it’s a number of players.

“Sometimes you’re best having your contract sorted out with an agreement that when an opportunity comes to move on that you can do that.”