Israel's foreign minister has said there is "no reason" to believe that his country's spy agency was behind the killing of a senior Hamas figure in the United Arab Emirates, but did not explicitly deny involvement.
Hamas has blamed Israel for the murder in a Dubai hotel room last month and the emirate's police force has refused to rule out the possibility that the 11 suspects wanted by investigators were working for Mossad.
Avigdor Lieberman, the Israeli foreign minister, told Army Radio on Wednesday: "There is no reason to think that it was the Israeli Mossad, and not some other intelligence service or country up to some mischief.
However, he also said that Israel has a "policy of ambiguity" on intelligence matters.
Theodore Karasik, director of research at the Institute for Near East and Gulf Military Analysis in Dubai, told Al Jazeera the operation appeared "too sloppy" to have been carried out by Mossad.
"They were clearly unprofessional ... in the sense that they were able to go out and come to Dubai knowing full well of the biometric system that's in place here and the passport control."
Dubai police have said that at least seven of the 11 members of the gang suspected of carrying out the killing of Mahmoud al-Mabhouh share names with foreign-born Israelis.
'Like an espionage movie'
Six of the men are Britons who immigrated to Israel. The seventh is an American-Israeli, whose name Dubai said was on a German passport used by one of the assassins.
But the Israelis have insisted that their identities were stolen and said the passport pictures were not a match.
Paul John Keally, an Israeli-British citizen whose identity was apparently used by one of the group, said his life has become "like an espionage movie".
"It is all very worrying but I know I have not done anything wrong," he was quoted as saying by Britain's Daily Mail newspaper.
The wife of Stephen Hodes, another British-Israeli living west of Jerusalem, told Israeli paper Maariv: "It started like a story that made us laugh, but now we don't know how to take it."
In the Gaza Strip on Wednesday, thousands of Hamas supporters attended a rally in honour of al-Mabhouh.
"The decision to avenge the martyr Mahmud al-Mabhouh has been taken, and it will be equal to the crime," Abu Obeida, a spokesman for Hamas's armed wing, told the crowd.
Shortly afterwards Khaled Meshaal, the exiled Hamas leader, gave a televised address from Damascus in which he again blamed Mossad for the murder.
"The time for promises and talk of revenge is done. Now is the time for action," he said.
On Tuesday, British and Irish officials said that they had examined the details of the nine suspects' passports purportedly issued by the two countries and said they believed they were fake.
Claims that Mossad may have counterfeited UK passports to allow Israeli agents to operate abroad triggered speculation that diplomatic relations between Britain and Israel could be harmed, but Lieberman said that was unlikely.
"I think Britain recognises that Israel is a responsible country and that our security activity is conducted according to very clear, cautious and responsible rules of the game"
Israeli foreign minister
"I think Britain recognises that Israel is a responsible country and that our security activity is conducted according to very clear, cautious and responsible rules of the game," he said.
"Therefore we have no cause for concern."
Gordon Brown, Britain's prime minister, has called for an investigation into how fraudulent UK passports were apparently used in the operation and Israel's ambassador to London has been summoned to the foreign ministry.
"The defrauding of British passports is a very serious issue. The government will continue to take all the action that is necessary to protect British nationals from identity fraud," a British government spokesman said.
Mossad hit squads have used foreign passports in the past, most notably in 1997 when agents entered Jordan on Canadian passports and bungled an attempt to kill Khaled Meshaal, the exiled Hamas leader, with poison.
Britain has previously protested to Israel about what London called the misuse by Israeli authorities of forged British passports and said it received assurances steps had been taken to prevent future occurrences.
French authorities have said a national passport used by one of the suspects had a valid number but incorrect name, while Austria has launched an investigation into the suspected use of at least seven mobile phones with pre-paid Austrian chips.
The group of suspects were linked together through videos which show them entering and exiting the hotel and going in and out of the elevator on the floor where al-Mabhouh was staying.
Al-Mabhouh was born in the Gaza Strip, but had been living in Syria since 1989.
He is said to have engineered the capture of two Israeli soldiers during a Palestinian uprising in the 1980s.