HITC Sport understands that there are still several issues to iron out in discussions regarding a permanent deal for last season's loan star.
Barcelona are ready to let him leave on a free transfer, but the player's personal demands are putting any chance of him returning to Upton Park at risk.
Song was hugely impressive during a year-long stay with West Ham last season and new Hammers boss Slaven Bilic has told the club's hierarchy that he would be more than happy to have him in his squad.
But HITC Sport understands there are several issues to resolve if a deal is to be done. Firstly, Song is struggling for fitness with a couple of niggling injuries, including a knee problem.
There are also his personal demands of a three-year deal worth over £70,000-a-week, which West Ham are not happy about committing to at this stage.
If a deal is not struck in the next week, then West Ham are ready to end negotiations.