Swansea have dismissed reports they have agreed to sell Gylfi Sigurdsson with owner Steve Kaplan insisting the club are determined to keep the Icelandic playmaker.Sigurdsson is expected to be in big demand this summer and reports on Tuesday suggested that Swansea had agreed a £25million transfer fee with Everton for the 27-year-old.But Swansea want to keep a player who scored nine goals and had 13 assists in the Premier League season just finished, with Kaplan revealing that the club's American owners spoke to Sigurdsson over the weekend."We all know how important Gylfi is, just as he knows how much he's valued and loved here," Kaplan told WalesOnline."There's been interest in him before - there were some pretty big enquiries about him last summer and in the January window - but we didn't want to sell him then and we don't want to sell him now."Swansea chairman Huw Jenkins revealed three months ago that Sigurdsson - who signed a new four-year contract last August - was the subject of "substantial offers" during the January transfer window.Everton have been linked with Sigurdsson for some time, but Swansea moved quickly to dismiss reports that a bid from the Toffees had been accepted."There has been no contact between Swansea City and Everton," said a club spokesman."As far as the owners, the chairman and the manager are concerned, they want to keep Swansea City's best players."Sigurdsson definitely falls into that category after an outstanding year which last week saw him named Swansea's player of the season.After winning the award for the second successive campaign, Sigurdsson said he was happy at Swansea and would only leave the Liberty Stadium if the club wanted to sell him."I signed a new contract in the summer and I've got three years left," Sigurdsson said."So it's down to the club if they want to sell me. But I was very happy when I was on loan here and then again in the last three years."I'm not trying to leave, I'm not desperate to go or anything."Sigurdsson has scored 37 goals in 131 appearances during two highly successful spells at Swansea.The former Hoffenheim player had a loan stint at Swansea in 2012 and returned in 2014 after a difficult two-year stay at Tottenham in which he completed 90 minutes in only nine of his 58 league games.