Premier League target Son Heung-Min may be sold this summer if he does not sign a contract extension with Hamburg, the club's sporting director Frank Arnesen has revealed.

The 20-year-old has established himself as a key figure in the Hamburg side this campaign, inevitably attracting the attention of a number of Premier League clubs. Tottenham Hotspur have been closely linked with a move as the season draws to an end, while Manchester United and Chelsea were credited with interest by Son's representative earlier in the year.

The German club have previously been resilient in their attempts to hold onto their prized asset, confident that the South Korean would commit himself to a contract extension. But with his current deal set to expire in the summer of 2014, Hamburg are growing increasingly concerned that Son may turn down their offers, forcing the club to cash in on the forward this summer.

Son Heung-Min
A move to the Premier League could await Son this summer. (Reuters)

Arnesen, who had spells in a similar role with both Chelsea and Tottenham, was blunt when quizzed on the forward's situation, stating, "If we cannot extend Son's deal, we have to sell him," he was quoted as saying in Bild.

Son has enjoyed an impressive campaign for the Bundesliga side, hitting a respectable 11 goals in 28 appearances for the club. Reports have suggested that Andre Villas-Boas and Spurs chairman Daniel Levy are both keen on bringing the Hamburg forward to White Hart Lane, but may also face competition from Champions League finalists Borussia Dortmund.

Despite having confirmed a date at Wembley with Bayern Munich later this month, the club will lose the influential Mario Goetze to the Bavarian giants this summer, and could see forward Robert Lewandowski follow suit. With the club likely to lose both of their integral attacking outlets, Jurgen Klopp's side are also reportedly considering a move for the sought-after Son.

In addition to Son's contract impasse throwing the forward's future in doubt, Hamburg may find themselves forced to cash in on one of their most prized assets this summer. The former European Cup winners are set to post record losses for the financial year, and with their hopes of stealing a Champions League spot all but gone, the German club may have to find other ways to refinance the club.