The Inter-American Commission on Human Rights Monday demanded the United States explain abuses allegedly committed at Guantanamo prison, especially its practice of force-feeding inmates on hunger strike.

"The information we have indicates that there was a general and systematic violation of human rights" in Guantanamo, said Rodrigo Escobar Gil, one of the Washington-based body's seven commissioners.

The allegations of forced feeding of Guantanamo prisoners on hunger strike constituted "cruel and inhumane treatment," he added.

"We want to know ... what research is being done about it" and "what steps have been taken to meet the demands of the prisoners," the commissioner said.

At its peak, some 106 out of 164 detainees were on hunger strike in protest against the legal limbo in which detainees are held at the prison, which is on a US naval base on the southeastern tip of Cuba.

According to US authorities, who say that the strike ended in late September after more than six months, up to 46 of the detainees were force-fed through nasal tubes at some point in the protest.

The government has argued in US court that the practice, called enteral feeding, "is used only when medically necessary to protect life and health."

The IACHR said Monday it wanted unfettered access to the prison camp to investigate.

"We have reports of torture and degrading treatment. But all our requests for visits without conditions have been denied. We want to know when they are going to allow visits without pre-conditions," Escobar Gil added.

The commissioner also requested the IACHR report on "the remaining obstacles to the transfer of prisoners to other countries," noting US President Barack Obama has promised to shut the camp.

But the US deputy representative to the commission, Lawrence Gumbiner, said his team could not answer issues raised at the hearing because the 17-day US government shutdown in October left them inadequate time to prepare.

"We respectfully propose to the commission to answer in writing in 30 days," Gumbiner said, generating a buzz of surprise.

Among those petitioning against the United States on Monday was UN Special Rapporteur against Torture, Argentina's Juan Mendez, who expressed disappointment after the session.

"This case is a decade old," Mendez told reporters, saying last month's partial US government shutdown was no excuse.

The regional human rights commission, an independent body of the Organization of American States, is holding its 149th session from October 28 to November 1.