Everton manager Roberto Martinez warned Chelsea they will be wasting their time if they try to sign John Stones during the January transfer window.

Chelsea relentlessly pursued Stones during the summer window and according to Sky Sports, the Toffees rejected three bids from the Premier League champions in one of the longest-running transfer sagas of the window.

Stones has continued to establish himself as one of the league's best young defenders this season, much to the frustration of Chelsea who are paying the price for not making a significant addition to their options at centre half.

The Daily Mail claim the struggling champions will reignite their attempts to sign the 21-year-old when the transfer window reopens while the Daily Telegraph suggest Barcelona are also now very interested in the player.

But the sale of any player at Goodison Park will not be up for discussion, says Martinez.

"From our point of view the window in January will be, as it has always been, to try and see if there is anything we can do to help the squad we have in place and, if there ever are any opportunities, we will always look into it," he told a press conference.

"But we don't look at this as a window where we will, be really involved, to bring players or to sell players. For us, it is more a matter of continuity. From now until the international break in March it is about developing the strongest possible squad we have."

When asked if the club were at a stage where they could firmly say their best players will not be sold, he added: "As I've said many times, we are not a position where we have to make financial decisions like that or balance any books. The focus is trying to be as strong together with the group we have."

Stones handed in a transfer request back in August during the height of Chelsea's chase but has shown little indication he is interested in move half way through the season.