Speaking to the ABC from Indonesia where she is investigating human rights issues, Ms Navi Pillay responded to reports that scores of those being held on Nauru had refused food.
She said it was an alarming indication that conditions are unbearable and said there should be efforts made to protect the asylum seekers' human rights.
"If that is done you wouldn't have people going on hunger strike," she said, adding that Australia has an obligation to provide humanitarian conditions.
"It would be a blight on Australia's good human rights record if it doesn't respect the rights of asylum seekers under the convention to which it is a party," she said.
Yesterday it was reported that all but one asylum seeker on Nauru had abandoned their hunger strike following news that representatives from Amnesty International would travel to the facility to hear their concerns.
Said Muhammad from Pakistan, who is acting as spokesman for the hunger strikers, claimed that at the peak of the protest 305 of the 386 asylum seekers on Nauru were refusing food.
This morning, Ian Rintoul from the Sydney-based Refugee Action Coalition told ABC Radio Australia's Pacific Beat program that six asylum seekers were continuing with the protest.
They include one Iranian man who is entering a 34th day without food.