The former Sweden international announced he was leaving LA Galaxy after two years in Major League Soccer. In October, he teased fans with a tweet in which he said he was "coming back to Spain" -- however, it turned out to be a stunt for a gambling company.
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On Tuesday, he tweeted a picture of a Hammarby shirt with his name on the back and a source with intimate knowledge of the situation told ESPN FC to "take it seriously."
Another source at Hammarby, however, refused to rule out the possibility of Ibrahimovic investing in the Swedish club when questioned about it by ESPN FC.
The owners of Ibrahimovic's former club LA Galaxy, Anshutz Entertainment Group, own 35% of Hammarby, while the ex-Manchester United forward still owns a house in Stockholm.
Hammarby are known for their attractive, attacking football and finished third in the Swedish top flight last season -- one behind winners Djurgadens -- and start next season in the Europa League first qualifying round.
Meanwhile, sources have told ESPN FC that Ibrahimovic wants an 18-month contract worth 6 million-a-season if he returns to AC Milan.
The 38-year-old spent two seasons with the Rossoneri, where he won a league title in 2010-11, but the club's board are split on whether to bring him back.
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