The chief of Dubai Police has denied a newspaper report saying the Australian Mossad agent known as Prisoner X had contacted his force to give details of Mossad's 2010 assassination of a senior Hamas official.
Lt Gen Dahi Khalfan Tamim denied the report that Ben Zygier, 34, an Israeli-Australian who apparently worked for Mossad, contacted police over the hit on Mahmoud Al Mabhouh in a Dubai hotel room in January 2010.
Zygier is the figure of much controversy in Israel, where he was secretly held in a prison until he committed suicide, according to authorities.
The Kuwaiti newspaper, Al Jarida, cited "western sources" as saying Zygier may have offered authorities details such as names and photos related to Mossad's drugging and killing of Al Mabhouh.
But late on Thursday Gen Tamim posted a response on Twitter to a journalist's question on the site.
"It's not true [about Zygier's alleged offer to Dubai], but maybe he committed suicide after he realised that he was a mercenary and a murderer, and became known to the world as a criminal fugitive from justice," he tweeted.
Gen Tamim did not address claims by the newspaper that Zygier had been under suspicion by Dubai Police for possible involvement in Al Mabhouh's assassination.
Al Jarida's report claimed Zygier, detained by Israel's Shin Bet internal security service in February 2010, may have been a member of the Mossad team that carried out the hit.
He may have been tracked down to his hiding place and arrested by Israel for betraying Mossad, then secretly placed in a solitary cell in a maximum security jail, the newspaper said.
The assassination of Al Mabhouh proved to be an international embarrassment to Israel.
Images of alleged members of the hit squad were captured on surveillance cameras at Dubai International Airport and at the five-star Al Bustan Rotana Hotel.
Those images allowed Dubai Police to uncover many of the agents involved by releasing more than two dozen of their photos online.
The life and fate of Zygier has drawn wide attention in Israel and abroad this week amid revelations about his imprisonment, and growing scepticism by some commentators of Israel's claim that he had committed suicide.
The affair has also attracted media scrutiny because of Israel's far-reaching efforts to try to keep the new details under wraps.
It used a rare mix of censorship measures, including a court-ordered media gag, urging top Israeli newspaper editors to avoid publishing anything on Zygier, and having the military censor take down Israeli web stories on the issue.
The new reports are raising questions about Israel's detention policies and may possibly affect its relations with Australia.
Tensions arose between the two nations three years ago after Dubai Police said Mossad agents had used almost a dozen fraudulent passports, including Australian, for Al Mabhouh's killing.
Australian media reported this week that Zygier had applied for three Australian passports using three identities over the years - Ben Alon, Ben Allen and Benjamin Burrows.
On Thursday, Australia's Fairfax Media reported Zygier had been "about to blow the whistle" on Israeli intelligence operations, including the use of fake Australian passports, to the Australian government or the media.
The Israeli government has kept silent on the issue except for a terse statement admitting Zygier was jailed and that his full rights were retained.
But coverage of the issue has been raging in the Israeli media.
The reports have raised demands from left-leaning journalists and activists for the government to launch an investigation into Zygier's jailing and death. It has also spurred criticism about the role of the Israeli justice system.
"The most troubling and problematic factor in the story is the Israeli justice system - not the Mossad, not the Shin Bet, prison service or the media," Uri Misgav, a commentator in the liberal Haaretz newspaper, wrote yesterday.
Misgav said he discovered that three district court judges chosen to try Zygier after he was jailed had decided to conduct proceedings "in complete darkness", even hiding the existence of the case from the public.
Michael Sfard, a prominent Israeli human-rights lawyer, was quoted in the column as blasting that decision as "a legal atrocity and a violation of the supreme principle without which a just trial cannot exist - openness to the public and public supervision".
Misgav also wrote that it was unlikely that Zygier committed a major offence against Israel as he was in talks with authorities on a plea deal, an unusual offer in cases of "severe treason or espionage".
* With additional reporting by Mohammed N Al Khan