Liverpool boss Brendan Rodgers, who made the switch from the Liberty Stadium to Anfield to replace Kenny Dalglish this summer, confirmed his interest in the Wales international last week. The south Wales club are disappointed, claiming Liverpool agreed not to make approaches for Swans players until next year.
A club spokesman said: "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."
Allen signed a four-year deal with Swansea last year but Rodgers appears keen to bring him to north-west England.
Swansea, who finished three places and five points adrift of eighth-placed Liverpool in the Barclays Premier League, are keen to keep their current players.
The spokesman 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."
Rodgers last week said: "I have a great relationship with Swansea but if there is a market for any of the players, I would like to be in that market.
"They respect that. He is a very talented player, which everyone knows but there is nothing more at the moment. When players come to a club such as Liverpool, it's never straightforward."