Sporting Lisbon are demanding a higher transfer fee for West Ham United target William Carvalho, according to Sky Sports News.

West Ham United remain in talks to sign William Carvalho and are desperate to bring him to East London but Sporting Lisbon are standing firm on their asking price.

William Carvalho has a release clause of £40m in his contract and the Hammers were hoping to get him for cheaper than that.

However, Sky sources understand that Sporting Lisbon will not sell Carvalho unless West Ham match his buy-out clause.

The Portugal international is very keen on a move to the Premier League and is looking to push this through but his current club are adamant that he will stay unless his release clause is matched.

The 25-year-old has played 137 games for Sporting Lisbon and 37 international caps for Portugal, making him an experienced player despite his relatively young age.

Predominantly a defensive midfielder, the Hammers were hoping that Carvalho could add some steel to the midfield and help protect the back four.

His addition would see him challenging with Pedro Obiang, Edimilson Fernandes, Cheikhou Kouyate and Mark Noble for the central midfield spots.

West Ham remain locked in talks as they try to thrash out a deal for the Portuguese midfield enforcer.