Israel has set up a specialist commando unit designed to carry out missions deep inside enemy territory amid growing consensus in government circles that military strikes must be contemplated if economic sanctions do not halt Iran's nuclear programme.

The "Depth Corps" has been organised with the aim of co-ordinating deep penetration operations in other countries at a time when the defence ministry acknowledges that the number of covert Israeli operations abroad has increased significantly in the last year.

The unit, headed by Major General Shai Avital, a former head of an elite reconnaissance squad, was ordered by the head of Israeli Defence Forces (IDF) to focus on undercover work. Defence ministry officials in Tel Aviv insisted that it was not "Iran specific" and is needed to co-ordinate a range of duties.

The Tehran regime has repeatedly claimed that Israeli, US and British agents are responsible for the assassination of six scientists involved in the country's nuclear programme – a charge refuted by London and Washington. Officials in Tel Aviv in general refuse to comment on covert action.

"Of course I see about the killings in the media. I see it happens", said Dan Meridor, the Minister for Intelligence and Nuclear Affairs. "Are they natural, are they unnatural? There are many stories coming from there."

"About these deaths of scientists, I don't know what to tell you. I do not know the effects of that. The fact that they continue to work on this programme despite sanctions means they want to get nuclear and are prepared to pay a heavy price," he said.

Mr Meridor stated that Israel will monitor the effects of the sanctions, including an oil embargo, imposed on Iran by the European Union as well as punitive measures taken by the US.

"Pressure is important here, to leave them in a state where they are on the threshold of getting nuclear weapons would be a mistake," he said.

While Israeli officials publicly say they are prepared to wait and see the effectiveness of the sanctions, many hold privately that they lack the bite to force Tehran to abandon its nuclear ambitions. The decision by India and China to continue importing Iranian oil, around 35 per cent of the country's total sales, will seriously hinder the attempt to choke off the revenue stream of Mahmoud Ahmadinejad's regime.

"It's definitely a blow," said David Hartwell, senior Middle East analyst at IHS Jane's, adding that Iran may have discounted prices to keep the Chinese and Indians on their side.

Israeli officials say that any military action must take place by the end of summer to prevent Iran moving more of its nuclear capabilities underground. They also point out that the Western powers which have imposed them are now fully aware of the dangers posed by the regime. Yesterday in Washington, James Clapper, the Director of National Intelligence, told a Congressional panel that Iran may launch terrorist attacks in response to a perceived threat.