Song played for Arsenal between 2005 and 2012, appearing in over 200 matches for the club before leaving for Barcelona.
He moved to Russia two years ago and became a first-team regular at Rubin, but the club are mired in financial difficulties and have reportedly failed to pay their players for the last four months.
Song is now training with his former club and on Wednesday shared a picture of himself wearing an Arsenal training top with the caption: ‘No pain, no gain.’
It is not yet clear whether Arsene Wenger will be tempted into offering Song, 30, a playing contract as he seeks to bolster his side ahead of the business end of the season.
As Song has been officially released by Rubin Kazan he will be able to negotiate with English clubs outside the January transfer window, but only if that club has space in their 25-man Premier League squad.
Song has also spent time at West Ham, and became something of a fan favourite during his two-year spell at the club.
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