Diafra Sakho has reportedly refused to travel to Austria with his West Ham United teammates for a pre-season tour.
The 26-year-old forward, who was absent from the club's US tour because of illness, is believed to be keen to leave the London club this summer.
Earlier this month, it was reported that Sakho had handed in a transfer request due to the club's public attempts to sign a new striker.
According to Sky Sports News, the Senegal international, who has scored 15 goals in 43 Premier League appearances, has told the club that he does not intend to travel to Austria for the next leg of their pre-season schedule.
Sunderland reportedly launched an £11m bid for Sakho earlier this summer, but West Ham turned them down.
Hamburg and Sevilla are also thought to be interested in the striker.