(Reuters) - Palestinian President Mahmoud Abbas warned on Tuesday that the death of any one of the hundreds of Palestinian prisoners on hunger strike in Israel would be a "disaster" and could trigger a backlash that might slip out of control.

"It is very dangerous," Abbas told Reuters on a day when the Red Cross urged Israel to transfer to hospital six detainees who it said were close to death after not eating for two months.

"If anybody dies today or tomorrow or after a week it would be a disaster and no one could control the situation," Abbas said in an interview at his office in Ramallah. "I told the Israelis and the Americans if they do not find a solution for this hunger strike immediately, they will be committing a crime."

Joining some who began fasting earlier, an estimated 1,600 Palestinian prisoners out of 4,800 launched a mass hunger strike on April 17 to protest against conditions in Israeli jails and to demand an end to solitary confinement and more family visits.

The prisoners include Islamists from Hamas and Islamic Jihad as well as members of Abbas´s secular Fatah movement.

The fate of the hunger strikers has touched a raw nerve in the Palestinian territories with daily demonstrations in the occupied West Bank and in the Gaza Strip to support the protest.

The International Committee of the Red Cross in Geneva called on Israel on Tuesday to transfer six prisoners who have forsworn food for around two months to hospital.

All six are in prison under Israel´s long-standing policy of detaining people without charge whom it suspects of security offences, including plotting attacks against Israeli targets. The six have been refusing food for between 47 and 71 days.

In a statement, the ICRC said that the six were in "imminent danger of dying", although it upheld their right to choose whether or not they wanted to receive treatment.

"We urge the detaining authorities to transfer all six detainees without delay to a suitable hospital so that their condition can be continuously monitored and so that they can receive specialized medical and nursing care," said Juan Pedro Schaerer, head of the ICRC delegation in Israel and the Palestinian Territories.

"Their main demands are for a resumption of family visits from Gaza and for an end to solitary confinement in Israeli places of detention," the ICRC said.

"TRAGIC"

Palestinian Prime Minister Salam Fayyad described the plight of prisoners as a "personal story for the Palestinians".

"The most tragic thing is if you look at the list of demands they have presented Israel ... they are generally related to the basic rights of prisoners," Fayyad told Reuters in a separate interview in Ramallah.

"There is a clear violation of the Geneva conventions."

The ICRC´s Shaerer stressed that the prisoners´ right to fast is protected by international conventions which discourage force- feeding: "While we are in favor of any medical treatment that could benefit the detainees, we would like to point out that, under resolutions adopted by the World Medical Association, the detainees are entitled to freely choose whether to consent to be fed or to receive medical treatment," he said.

"It is essential that their choice be respected and their human dignity preserved," he said.

Israeli government spokesman Mark Regev said Israel was providing medical treatment for the prisoners and they were free to choose their own doctors if they wish: "But ultimately, this is not about medical facilities," he said. "This is about hard-core activists, from Hamas and Islamic Jihad, who through this protest are trying to instigate violence."

On Monday, Israel´s Supreme Court turned down an appeal by two of the Palestinian detainees.

But in its decision the court said Israeli authorities should consider freeing them on medical grounds.

The scope of the hunger strike has posed a new challenge to Israel, which has come under international criticism over detentions without trial and could face a violent Palestinian backlash if any of the protesters die.

The office of United Nations High Commissioner for Human Rights Navi Pillay also voiced concern for the strikers´ fate.

"International law is clear: administrative detention should only be used in exceptional cases and only for imperative reasons of security. Administrative detainees have the right to challenge the lawfulness of the detention," spokeswoman Ravina Shamdasani told a news briefing.

Independent U.N. investigators and U.N. rights bodies have raised concerns about Israel´s frequent and extensive use of detention without trial, including of children, infringing on detainees right to a fair trial, Shamdasani said.

(Reporting by Stephanie Nebehay in Geneva and Samia Nakhoul in Ramallah; Editing by Alastair Macdonald) (© Thomson Reuters 2012. 05/08/12)