Swansea City insist they will not be bullied into lowering their asking price for Gylfi Sigurdsson amid strong interest from Everton, warning potential suitors against attempting to 'tap up' the Icelandic playmaker.

Sigurdsson did not travel to Philadelphia on Thursday (13 July) for a pre-season tour of the United States, with Swansea confirming that he "did not feel in the right frame of mind to travel due to the current uncertainty over his future." He initially returned to action on the previous evening, where he made a 45-minute cameo and captained Paul Clement's side in a surprise 1-0 defeat at Barnet.

The Telegraph reported that Everton had failed with an initial club-record offer of £40m ($51.9m) for Sigurdsson, although it was claimed that negotiations would continue and that a deal could be concluded this week.

Clement also conceded that the 27-year-old was subject to "strong interest" and could follow new Burnley midfielder Jack Cork out of the Liberty Stadium exit door providing a very good offer is received.

Leicester City have also pursued Sigurdsson over recent weeks and it was their own failed £40m offer that led the BBC to report that Swansea were holding out for a fee of £50m.

Speaking in a statement released to WalesOnline, the club's American owners, Jason Levien and Steve Kaplan, expressed disappointment with Sigurdsson's decision not to travel to the US and maintained that they would not be pressured into selling their star man for a cheaper fee.

They also provided a stern reminder that any pre-agreement reached with the player, who scored 10 goals and provided 13 assists in 40 appearances across all competitions in 2016-17 to help Swansea preserve their top-flight status, would breach Premier League rules.

"We are disappointed Gylfi has taken the decision not to join his teammates in America where they are working with the coaching staff to prepare for the upcoming season," they said. "At this time we have not received an offer from any club which represents a fair valuation of Gylfi given his importance to our club.

"As we have stated, we will not be bullied or forced into a decision until a club meets our valuation of the player, no matter whether they believe they have an agreement with the player. Any such agreement would obviously be in contravention of Premier League legislation."

Levien and Kaplan further claimed to have the "ultimate respect for Gylfi as a person and a player" and said they were "optimistic that he would reconsider" his decision not to join the rest of his teammates across the Atlantic for an 11-day tour that includes three friendly fixtures against the Philadelphia Union, Richmond Kickers and North Carolina FC.

Gylfi Sigurdsson
Gylfi Sigurdsson in action for Swansea against Barnet on Wednesday evening Nigel Roddis/Getty Images