The assassins of a senior Hamas militant in Dubai made use of diplomatic passports, the Gulf emirate's police chief said on Sunday, as he warned of a mole within the ranks of the Palestinian group.
Britain's Sunday Times newspaper, meanwhile, said the killing was carried out by Israel's spy agency Mossad with the green light and blessing of Prime Minister Benjamin Netanyahu.
"There is information that Dubai police will not make public for the moment, especially regarding diplomatic passports" used by some of Mahmud al-Mabhuh's killers to enter Dubai, police chief Dahi Khalfan said in Al-Bayan newspaper.
Mabhuh, a founder of the armed wing of the Palestinian Islamist movement Hamas, was found dead in his hotel room in Dubai on January 20.
Last week, Khalfan released the names and photos of 11 murder suspects with European passports -- six from Britain, three from Ireland, one from Germany and one from France.
The use of European passports has sparked a diplomatic furor in which Israeli envoys in the four countries have been summoned for talks.
But on Saturday, Israeli Deputy Foreign Minister Danny Ayalon insisted there would be no diplomatic crisis with Europe over the use of foreign passports in the Mabhuh murder "as Israel had nothing to do with what happened."
Khalfan, however, has said he is "99, if not 100 percent" sure that Mossad was behind the assassination, and added on Saturday that Dubai had evidence, including wiretaps, of the agency's role.
The Sunday Times said the killing was personally approved by Netanyahu, citing sources with knowledge of Mossad.
The premier met members of the hit squad at Mossad headquarters shortly before they travelled to Dubai, according to the Sunday Times, and authorised the mission, which was not seen as complicated or risky.
"Typically on such occasions, the prime minister intones: 'The people of Israel trust you. Good luck,'" the paper added.
Khalfan said that Mabhuh's killing was "no longer a local issue, but a security issue for European countries," quoted on Sunday in another Emirati daily, the Abu Dhabi-owned Al-Ittihad.
Al-Ittihad said Khalfan has called for Hamas to conduct an internal investigation "about the person who leaked information on Mabhuh's movements" and arrival in Dubai to his killers.
The source of the leak was the "real killer," Khalfan was quoted as saying.
He said last week in a Dubai TV interview that there were others implicated in the killing whose names have not yet been made public.
And two Palestinians have been arrested in Jordan and extradited to Dubai, where they are being held in connection with Mabhuh's death, according to Khalfan.
A Palestinian Authority security official in the West Bank identified the two as Anwar Shaheiber and Ahmed Hassanein, members of the PA security forces which Hamas ousted from Gaza in deadly clashes in 2007.
A senior Hamas member, Nehru Massud, was also suspected of involvement in the killing, the official said.
Massud, however, has denied any involvement in the murder, while Hamas has denied reports that he has been detained in Syria in connection with the killing.
Hamas has blamed the killing entirely on Israel and vowed revenge.