Roberto Martínez has said Everton would not consider selling Ross Barkley in January even if the club received an offer similar to the world record £86m that took Gareth Bale to Real Madrid.

The 20-year-old midfielder gave another demonstration of his prodigious talent on Sunday at Swansea City with a fine second-half display and a stunning free-kick that sealed Everton's 2-1 win. The boyhood Evertonian has attracted comparisons to Michael Ballack and Paul Gascoigne during his first full season as a first team regular at Goodison Park, and earned three England caps from Roy Hodgson before a World Cup summer in Brazil.

But with Barkley's star rising amid a dearth of young English talent, Martínez has told prospective suitors that they would be wasting their time making any offers for Everton's homegrown talent when the transfer window opens on New Year's Day. The Everton manager claimed that the club's resolve would not weaken in receipt of a bid in the Bale price-bracket.

Martínez said: "Ross is in a moment of his career where first, he knows that he needs to carry on developing and this is the perfect place to do that. Second, he is a mad Evertonian and enjoying every single second. And third, we are in the middle of a season where we would never, ever consider disrupting what we have got in our squad now.

"It is not the right time for the player or the club to consider anything. Even if we got a Gareth Bale-size valuation we would never even consider it in January."

Everton made similar noises about Wayne Rooney when he first emerged at Goodison Park only to sell for £27m when he pushed for a move to Manchester United in 2004. While accepting every player has his price, Martínez insists Everton are a different proposition on and off the pitch than when Rooney left for Old Trafford nine years ago.

He added: "What you need to understand is that you cannot fight against the trend of the modern game. You saw it with Gareth Bale, with Cristiano Ronaldo; that is the nature of the modern game. What is very important is that if anything happens, it is our club that dictates how and when. If we had a financial problem or were facing a financial disaster then we would not be in control of those aspects and I would be telling you: 'Look, we are in the lap of the Gods.'

"We are not in that situation at all.

"We are probably in the strongest financial position we have been for a long time. All we are going to make is football decisions. If we were going to lose a player it would be to end up with three or four replacements and in a stronger position. That is always the case. Ross is an icon for us. He represents everything we are trying to do this season, so even if a stupid offer arrived in January it would never affect us. It is important for us as a football club to show we are making the right football decisions."

Barkley has two and a half years remaining on his Everton contract and the club will look to secure the midfielder on a new long-term deal before the end of the season. Martínez, who Barkley has thanked for providing more regular first-team football this season, believes the midfielder appreciates the fact that he remains in the early stages of his development with Everton.

"I've never met an elite footballer with such a strong winning mentality who is so down to earth. He is so realistic about what he has to do," the Everton manager said. "What he has done on the pitch has caught a lot of attention but Ross is still a very young man and is still developing.

"With Ross Barkley, or any youngster, it's about measuring them when they have had between 75 and 100 starts in the Premier League. He is in the middle of the best moment in his career [so far] right now. There is no question mark over Ross's future, he is in the best moment of his time and is everything we want a player to represent at Everton. There is not even a question mark against whether he is going to be here in February or not."