A hit squad that murdered a senior Hamas official in Dubai used the stolen identities of six British citizens and faked at least five other European passports, it emerged today.

The international investigation into the assassination of Mahmoud al-Mabhouh last month is certain to examine the role played by Israel, where as many as seven of the victims of identity theft, including at least four Britons, are currently living.

Some reports yesterday suggested a team of 17 people were involved in the meticulously-planned killing. Six have yet to be identified.

Official sources said UK authorities issued the British passports used by the assassins in Dubai last month.

They confirmed that the killers had not altered the names and numbers in the passports, but the photographs had been changed.

At least six of the people whose names appeared on British passports used by the assassins in Dubai live in Israel. All deny any involvement.

"I am obviously angry, upset and scared – any number of things," Melvyn Mildiner, one of them, told Reuters. "And I'm looking into what I can do to try to sort things out and clear my name."

Israeli press reports named three other British Israelis whose identities were used – Paul Keeley, Stephen Hodes and Michael Barney – as well as Michael Bodenheimer, who emigrated from the US 30 years ago but whose name appears on one suspect's German passport.

Two others living in Israel were identified as James Clark and Jonathan Graham, whose names are almost identical to those appearing on two forged British passports used by the suspects.

The revelation fuelled already widespread speculation in the region over Mossad involvement in the killing of Mabhouh and an orchestrated plot involving 11 assassins, mostly posing as tourists in Dubai.

Mabhouh was one of the founders of the military wing of Hamas and had been wanted by Israel for his role in the 1989 kidnapping and killing of two Israeli soldiers on leave. His participation was acknowledged by Hamas last month.

The Israeli government would not comment on allegations of its involvement in Mabhouh's killing.

If confirmed, the allegations would trigger a diplomatic row with Britain and the other three European nations whose passports were used – Ireland, Germany and France.

The Irish Republic said the three Irish citizens named by Dubai police as suspects did not exist, while the German government said the passport number of the sole German suspect was either incomplete or wrong.

The authorities in Paris refused to comment on the authenticity of a French passport used by one of the killers.

Dubai public prosecutors have issued warrants for "premeditated murder" against the 10 men and one woman in the suspected team of assassins – the first step in obtaining a "red notice" from Interpol to track down wanted fugitives abroad.

Police in the emirate described the killing as meticulously planned, with the hit squad arriving on different flights and checking into different hotels.

They were seen on surveillance video tailing Mabhouh from the moment he arrived in Dubai.

His murder, in his hotel room near Dubai International airport, took 10 minutes, and early forensic tests suggest that he was suffocated.

The assassins left on flights to Europe and Asia before the body was discovered on 20 January.

Authorities in the United Arab Emirates identified Austria as a possible "command centre" for the operation.

In a sign that the country would be seeking formal assistance from European states, the Dubai attorney general, Essam al-Humaidan, told the Abu Dhabi-based National newspaper that the UAE had signed judicial treaties with certain European countries, enabling the "extradition of the suspects wherever they hide".

Michael Levi, a Cardiff University professor of criminology and an expert on identity theft, said that if the British travel documents used by the assassins predated the introduction of biometric e-passports, they would not be hard to tamper with.

"The sort of organisation that can pull off a hit like that will be able to make those sort of changes," he said.

"The point is that, in any system, you only have to be good enough to pass the scrutiny of the people you're going to come across."

The Foreign Office said it was too early to speculate on who could have carried out the identity theft against the British citizens involved.

In recent decades, Mossad has gained a reputation for using passports of other countries, and Britain had a diplomatic row with Israel in 1987 over its use of forged British passports.

In 1997, a Mossad hit squad used doctored Canadian passports in a botched attempt to kill the Hamas leader, Khaled Meshal, while two suspected Israeli agents were jailed in New Zealand in 2005 for obtaining the country's passports illegally.

Rami Yigal, a former Mossad official, told Israel Army radio the assassination "doesn't look like an Israeli operation".

There was a mixture of praise and criticism of Mossad in the Israeli press today.

Yossi Melman, a respected security correspondent for Ha'aretz, said Mossad had used forged passports on operations in the past and noted that, in this case, all the "operatives" involved in the assassination had left Dubai without being caught.

"As such, unless dramatic evidence is found to definitively prove an Israeli connection, it is likely that the state of Israel will emerge from this affair unblemished and Mossad will continue enjoying a reputation of fearless determination and nearly unstoppable capabilities," Melman wrote.

However, another Ha'aretz columnist, Amir Oren, said there were now "enormous question marks" over the operation and said the Mossad chief, Meir Dagan – whom he described as "belligerent and heavy-handed" – should quit.

He said the case was likely to bring a diplomatic crisis for Israel and added: "But even if whoever carried out the assassination does reach some kind of arrangement with the infuriated western nations, it still has an obligation to its own citizens."