A hunger strike at Guantanamo Bay, Cuba, has spread over the past two weeks, with the U.S. military saying the number of detainees participating in the protest has more than doubled and attorneys for the men insisting that the number is far higher.

The Pentagon said Monday that 39 men are consistently refusing food. Of those, 11 are being force fed — a process that can involve strapping the detainee down and passing a liquid nutritional supplement through a tube that is run from the nose into the stomach. Attorneys for the detainees, who visit the military detention center or speak to their clients by phone, said nearly the entire population of Camp 6 — where detainees can use common areas — is on hunger strike. Until recently, 130 detainees were kept in Camp 6, but it’s unclear how many remain. The lawyers said some of the protesters have been moved to the adjacent Camp 5 complex, which has been used to hold “non-compliant” detainees in greater isolation.

The military refuses to give specific numbers for the population of each camp. There are 166 detainees at Guantanamo Bay.

Detainees have covered the cameras inside Camp 6, making it difficult for the guard force to monitor conditions and raising fears that the condition of some detainees could deteriorate unnoticed, according to the miliary and lawyers.

Attorneys for the detainees said the immediate catalyst for the protest, which began in early February, was a decision by the camp authorities to search the detainees’ Korans. The military acknowledges that Korans were searched for contraband, but said they were handled only by interpreters, most of whom are Muslim, not the guard force.

David Remes, a lawyer for some of the detainees, said that most of the hunger strikers would resume eating if the military agreed not to search Korans — as it had not done before February for a number of years. But he added that a number of men want to expand the strike to protest their indefinite detention and what they consider the Obama administration’s abandonment of its plans to close the facility.

“These men, including many of my clients, say they are determined to leave Guantanamo one way or the other — alive or . . . in a box,” Remes said.

In a statement Monday, the International Committee of the Red Cross said 13 delegates, including a medical doctor, are visiting the camps. “It is the opinion of the ICRC that past and current tensions at Guantanamo, including hunger strikes, are the direct result of the uncertainty faced by detainees,” said Simon Schorno, a spokesman for the organization.

The ICRC does not report publicly on the conditions it finds at the camps or provide information on how many detainees it thinks are on hunger strike.

Remes said only two of the detainees would meet with the ICRC because, he said, the international organization’s presence helps the U.S. military legitimize its operations.

Separately Monday, Human Rights Watch called on Defense Secretary Chuck Hagel to allow the New York-based group “full access to Guantanamo Bay detention camps so that we can independently review and report on the conditions of confinement.”

The group also noted that President Obama issued an executive order more than two years ago on the creation within one year of a periodic review board to allow detainees to challenge their detention with the help of counsel. Despite the order, the review process has not started, adding to detainees’ frustration, lawyers said.