The 24-year-old striker was on the radar of Premier League clubs last summer, but he decided against leaving the German club.
A shoulder injury made him miss most of the first half of the season and he only recently returned to action, scoring three times in the league since getting back into the team.
West Ham and Tottenham are keeping tabs on the forward with a view to potentially signing him in the summer.
And there are likely to get a boost as according to German magazine Kicker, the Austrian will reject an offer of a new deal from Stuttgart.
His current contract will have a year left on it at the end of the season and the German club have been working towards tying him up on a fresh contract.
But it has been claimed that Kalajdzic will not be signing a new contract with the Bundesliga outfit.
It is likely to trigger the club to want to sell him in the summer in order to avoid the possibility of him leaving on a free transfer next year.
