The Daily Star Sunday says the player's agent Alexander Busac claims a move to the Premier League is still on.
Southampton had agreed a fee for Buttner earlier this month and the star, 23, had expressed a wish to clinch the deal.
But reports claim the involvement of a third party scuppered the transfer and Buttner is now training with Vitesse's reserves as the Dutch club do not expect him to be part of their plans.
Busac said: "There is a lot of interest. Hannover and Fulham are serious."