John Stones
John Stones is one of the Premier League's most in-demand playersGetty Images

Roberto Martinez has denied he has agreed to sell John Stones in the summer. The 21-year-old defender has been persistently linked with a move away from the club in recent months, but the Toffees boss has rubbished talk the pair already have a gentleman's agreement in place.

Stones was the subject of numerous bids from Chelsea in 2015 and the Blues are one of a number of clubs thought to be interested in the England international. However, Martinez has slammed the suggestion he has already agreed to a transfer.

The Spaniard said: "That is not true. I would never do that. It would be very negative. If you do that could you imagine the last two months for that player? He would never put a leg in or never challenge for the ball."

The Everton manager said such an agreement would only work if it had been in place for a 12-month period, thereby giving the manager plenty of time to find a replacement.

"I know you can do that to keep a player for another 12 months. But if you're not going to have a player 12 months down the line you need to start replacing him to have a stronger team," he said, according to The Guardian.

Martinez's remarks come shortly after Stones's former boss David Moyes hailed the progress the youngster has made since joining Everton in 2013. "He's improved his overall defending, he's got a natural ability to take the ball which is not something that's coached. He's reading the game much better.

"There are one or two occasions when part of being a defender is putting your foot through the ball. He did brilliantly to make himself a bit of space to clear the ball [when] there wasn't a pass on for him [against Tottenham]. That's John... he'll develop and he's made one or two mistakes which have cost him, but obviously he's going to go on and play for England for a long time," the ex-Everton manager explained following their 1-1 draw against Tottenham Hotspur.