Manchester United have reportedly told Inter Milan that they will need to include Ivan Perisic in any deal to take Anthony Martial to San Siro.
Martial is understood to be eager to leave Old Trafford in search of more regular first-team football, having made only one Premier League start so far this season.
Inter were keen on a loan deal for the France international in January, but the prospect of reaching an agreement has been made less likely by United's latest demands.
The Mirror reports that United have told Inter that they will need to trade long-term target Perisic for Martial, even to secure the 22-year-old on loan.
Inter are not willing to consider selling Perisic in January, so any prospective deal for Martial is no longer expected to happen until next summer at the earliest.
Perisic already has two Serie A goals to his name this season.