The Wales international is a target for recently-appointed Reds manager Brendan Rodgers, who is keen to snare the midfielder from his former club.
Reports on Wednesday suggested a £15 million move was in the offing after Liverpool confirmed their interest in Allen.
However, Swansea are furious with their Premier League counterparts, claiming the Merseyside outfit had agreed not to make any approaches for their players until next summer.
"Swansea can confirm that Liverpool have expressed an interest in Joe Allen, despite a written agreement with Liverpool not to approach any players within the 12-month period of former manager Brendan Rodgers leaving for Anfield," a club spokesman said in a statement on the club’s official website.
"There has also been interest from other clubs regarding his possible availability and the club is due to speak to Joe, as originally planned, about the situation when he returns from GB [Olympic] duty.
"The club is not prepared to release any details on whether any formal bids have been made at this stage or details of Joe's contract, which are private and confidential.
"The club is extremely disappointed that speculation regarding certain aspects of his contract have been released to the media by parties outside the club."
Swansea, who are keen to keep hold of their prized assets this summer, added: "Fortunately the club is in a financial position where it does not need to sell any of its players and will continue to work in the best interests of its supporters, who are our priority, and the club to provide new manager Michael Laudrup with the best opportunity to be successful in the forthcoming Premier League campaign."
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