Roberto Martinez has insisted that James McCarthy is not available to purchase this summer, despite reported interest from both Tottenham Hotspur and Manchester City.

The Republic of Ireland international has become one of the club's key assets since moving to Goodison Park from Wigan Athletic for £13m ($20.2m) in September 2013. He made 37 appearances in all competitions last season after recovering from a recurrent hamstring problem.

According to recent reports from The Mirror, Tottenham are long-term admirers of McCarthy. Manuel Pellegrini is also now thought to be tracking him the player, following City's failure to entice Fabian Delph from Aston Villa and no progress having been made in the pursuit of Juventus' Paul Pogba.

£20m is the figure the Manchester Evening News believe the player to be worth, although Martinez is defiant that Everton do not need to offload the player in order to improve their finances.

"He's not for sale," the Spaniard, whose side progressed to the final of the Barclays Asia Trophy yesterday (15 July) following a penalty shootout victory over Stoke City in Singapore, was quoted as saying by The Guardian.

"My responsibility is to bring competition into the squad and we have strong competition for places. We don't want to lose that. We're not in a position where we have to sell to balance the books and we want to create a winning team.

"James McCarthy is a top performer. He has shown that over recent years. We know what he brings with young legs and good energy. He's a vital part of our squad."

Tottenham have let a number of midfielders depart White Hart Lane already during the current transfer window as Pochettino seeks to re-mould his squad ahead of another attempt to crack the Premier League's top four and avoid yet more time spent in the gruelling Europa League.

Lewis Holtby's loan spell at Hamburg was converted into a permanent arrangement at the beginning of July, while Brazilian Paulinho has since joined Guangzhou Evergrande and Etienne Capoue was sold to newly-promoted Watford.

Manchester City, meanwhile, were believed to be close to agreeing a deal to sign Delph last weekend in a move that would provide a timely boost to their homegrown player quota, only to be rebuffed when the Villa captain clarified his ambition to stay put in a statement released via the club's official website last weekend.

City had more luck with their efforts to sign Raheem Sterling from Liverpool, however, with the 20 year old finally bringing an end to a particularly protracted and unpleasant transfer saga by agreeing terms on a five-year deal for a club record fee.