Sunderland are insisting on a fee for defender Santiago Vergini.
The Sunderland Echo says the Black Cats have rejected a proposal from suitors Boca Juniors to sign the defender for free.
Vergini faces an uncertain future when he returns to Wearside at the end of next week after last season's loan spell at relegated La Liga outfit Getafe failed to materialise into a permanent switch.
The Argentine international – sent out on loan by Allardyce's predecessor Dick Advocaat – has been attracting interest, most notably from his homeland where Boca are understood to have made contact with Sunderland.
However, it is thought that Boca's initial offer was to sign Vergini on a free transfer, which has been turned down by Sunderland.