Israel on Sunday said it was vigilant ahead of the Olympics in London but denied a report in Britain's Sunday Times that it had sent a team to hunt down militants preparing an attack on its athletes.
"There is definitely vigilance in terms of intelligence and operationally ahead of the Olympic Games," Defence Minister Ehud Barak told reporters.
"Naturally it is an attractive event, and even without concrete warnings, we must be ready and alert, first and foremost because such things have already happened," he said, referring to a deadly attack at the 1972 Munich Games which left 11 Israelis dead.
"We remember Munich."
According to the report, Israel has upped its level of security around its Olympic delegation in the wake of Wednesday's deadly suicide attack at Bulgarian resort on the Black Sea which killed five Israeli tourists and their local driver.
The report also said Israel had dispatched a team of agents from its Mossad foreign intelligence services to Europe to track down militants planning such an assault attack in conjunction with Lebanon's Hezbollah militia and the Quds Force, the special operations unit of Iran's Revolutionary Guards.
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But Amos Gilad, head of policy at Barak's office dismissed the report as fiction.
"Intelligence doesn't work like that, you don't suddenly send dozens of agents to chase phantoms," he told Israel's army radio.
"There has to be precise information and a rigorous collection of information," he said, describing it as "ant's work."
"We have to keep cool headed and balanced. There are attempts by Hezbollah and Iran in all sorts of countries, but.. we must try and keep a sense of proportion, despite the difficulty of the situation."
Quoting unnamed security experts, the Sunday Times said the Quds Force had recruited several white European converts to Islam, including two from Germany, one from Sweden and two Britons.
The fear is they could carry out a repeat of Munich massacre which left 11 members of the Israeli Olympic team dead, among them five athletes, four trainers and two referees.
So far, Bulgarian officials, working with the CIA, FBI and Interpol, have yet to identify the suicide bomber behind Wednesday's attack, although Israel has blamed Iran and its Shiite ally Hezbollah.
Washington has also said the bombing bore the "hallmarks" of a Hezbollah attack.
Israel's 38-strong team of athletes arrived at the Olympic village in Stratford, east London, 12 days ago as Britain prepares to launch its biggest ever peacetime security operation.