JERUSALEM - The son of a Hamas leader in the West Bank has told an Israeli newspaper that he was the "Green Prince", a key informer who provided Israel's intelligence services with crucial information for more than a decade.
Mosab Hassan Yousef, 32, is the son of Hassan Yousef, a founder of Hamas in the West Bank who is serving a six-year prison sentence in Israel.
His intelligence is said to have helped Israel's Shin Bet intelligence service to prevent dozens of suicide bombings and led to the arrest of top Palestinian leaders.
"So many people owe him their life and don't even know it," his former handler told Haaretz.
"People who did a lot less were awarded the Israel Security Prize."
The claims were dismissed by Hamas as a "Zionist ruse", but independent analysts in the West Bank said they were plausible.
If widely believed, they would deal another blow to the prestige of Hamas, already reeling from the assassination of the armed wing leader Mahmoud al-Mabhouh in Dubai last month, apparently by Israeli agents.
Dubai police say a Hamas member facilitated the killing, and Hamas has been at pains to deny there was a security breach.
Yousef, who now lives in California, has gone public with his claims ahead of the publication of a memoir, Son of Hamas.
"I wish I were in Gaza now. I would put on an army uniform and join Israel's special forces in order to liberate Gilad Shalit [the Israeli soldier held captive since 2006 by Palestinian militants]."
He was persuaded to work as the "Green Prince" - a nickname derived from the colour of the Palestinian flag and his own status as the son of a key Hamas figure - in 1996, while he was in an Israeli prison.
Throughout the early years of the second Palestinian uprising that broke out in 2000, he was considered the agency's best source inside Hamas, and contributed to the arrests of the suicide bombing mastermind Abdallah Barghouthi, now serving 67 life sentences, and the firebrand Fatah leader Marwan Barghouthi, according to the newspaper.
"One insight of Mosab was equal to a thousand hours of thought by the biggest experts," his handler, identified as Captain Louai, told Haaretz.
He described how Yousef worked in central Ramallah to identify a suicide bomber about to pick up his explosive belt. "We did not know what he would look like or his name, only that he was in his early twenties and was wearing a red shirt. We put the Green Prince in the square, and he located the objective within minutes. It led us to the arrest of the suicide bomber and the person who was supposed to give him the belt."
Hamas said the Haaretz report was aimed at discrediting the movement as a whole and Sheikh Yousef in particular.
"This is aimed at stirring up media noise to cover for the occupation's responsibility in the assassination of al-Mabhouh," Hamas spokesman Sami Abu Zuhri said.
But Hani Masri, head of the Bada'il think-tank in Ramallah, said it was plausible that Yousef, who converted from Islam to Christianity in 2005, had changed sides in the conflict. "He left not only Hamas, he left Islam as a whole." he said.
"For a Muslim, renouncing Islam is no less serious than going to the Shin Bet."
The report enables the Israeli intelligence community to claim a success at a time when the Mossad foreign espionage agency is being criticised for alleged identity theft in using forged British, Irish and other passports and for being caught on film in advance of the assassination.
But Mosab Yousef's comments are pessimistic about the chances of Hamas making an accommodation with Israel.
"It is against what God said to them, that you can't make peace with infidels, just a ceasefire. Who knows this better than me?"