Authorities in Iran intensified their campaign to blame the country's political turmoil on foreigners today by banning contact with more than 60 international organisations.

The intelligence ministry said the blacklist included thinktanks, universities and broadcasting organisations identified as waging a "soft war" aimed at toppling Iran's Islamic system.

It forbade Iranians from talking to or receiving aid from the proscribed organisations, including the BBC, which last year launched a Farsi satellite television channel, as well as two US government-funded outlets, Voice of America and Radio Farda, both of which broadcast in Farsi.

Also on the list were Wilton Park, a British group that organises foreign policy conferences, Yale University and leading American thinktanks, including the Brookings Institution and the George Soros Open Society Foundation.

While there have been previous cases of Iranians being arrested or harassed over involvement with some of the named organisations, there has never before been an extensive formal list.

The ban also included an Iranian reformist website, Rah-e Sabz, which has been a news source for international media during the recent unrest, which foreign journalists have been restricted from covering.

An unnamed deputy intelligence minister for foreign affairs was quoted by the state news agency, Irna, as describing Rah-e Sabz as "counter-revolutionary". Contact was "prohibited and considered as co-operation with foreign overthrowing organisations", he said.

The minister said the contact ban was a response to what he said was a concerted western policy of undermining the Islamic system through reaching out to influential "special groups", including experts, artists and academics, under the cover of cultural and scientific exchanges.

"Our revolution has become a target to be overthrown by the intelligence services of some countries, particularly America and Britain, and they have established soft invasion and overthrow strategies against the Islamic republic of Iran," he said. "They have allocated extraordinary formal budgets to fulfil this aim."

Iranians were also banned from unspecified "irregular contact" with foreign embassies or foreign citizens.

The blacklist was published after the intelligence minister, Heydar Moslehi, said on Monday that foreign and dual nationals had been among those arrested amid violent disturbances that broke out during last month's Ashura ceremonies. No detained foreign citizens have been named, although one was said to have been carrying a British passport.

Senior clerics and others have been urging the government to try opposition leaders as mohareb, or those fighting against God – a charge carrying the death penalty.The prospect of those identified as protest leaders being executed was heightened by the interior minister, Mostafa Muhammad Najjar, who told Irna: "After Ashura, anyone who takes part in riots will be considered as mohareb.

Gholamhossein Elham, the official spokesman for Mahmoud Ahmadinejad's government, raised the possibility of repeating the public mass trials of opposition activists which followed last June's disputed presidential election. "Holding an open trial for the leaders of the sedition will disgrace the leaders of the grand sin in history," he said.

Separately, Ahmadinejad's website was unobtainabletoday after reportedly being hacked. Those trying to enter saw the message: "Dear God, In 2009 you took my favourite singer Michael Jackson, my favourite actress Farrah Fawcett, my favourite actor Patrick Swayze, my favourite voice Neda. Please don't forget my favourite politician Ahmadinejad and favourite dictator Khamenei [Iran's supreme leader] in the year 2010. Thank you."