Amnesty International says a barrier installed at Manus Island's detention centre in Papua New Guinea could be tantamount to torture if it is making it difficult for detainees to access food.
That followed reports of a brawl breaking out between inmates and guards at the detention centre on Saturday, when a dispute over food turned violent.
A Kurdish journalist and detainee Behrouz Boochani has said the brawl was sparked by a new barrier erected to manage the line of detainees queuing for their meals.
He alleges the guards put up the barrier because they believe some detainees are taking more food then they should.
Amnesty's Pacific Researcher Kate Schuetze said the camp was obliged to provide the inmates with an adequate amount of food.
"Ridiculous things such as creating barriers and making it more difficult for people to access food in and of itself could amount to a violation on the prohibition against torture, if in fact it is denying people access to meals."