Tehran is seeking to developing a national Internet system, which it says would improve cyber security. But many Iranians say the plan is the latest way to control their access to the Web, which is already highly censored.

Iran’s hardline clerical leaders are determined to prevent any new wave of unrest after the bloody turmoil that followed President Mahmoud Ahmadinejad’s disputed re-election in 2009.

But street protests erupted last week over the plunging value of the rial, which lost a third of its dollar value in 10 days as Western sanctions on Iran’s oil and banking sectors cut the country’s ability to earn hard currency from oil exports.

Very little trading occurred on the open market on Monday, with the government-promoted rate of 28,500 rials to the dollar attracting little interest among those with dollars to sell.

The authorities have pressed dealers to trade dollars at certain rates and have arrested money changers accused of speculating. Others, unwilling to use state-set rates and afraid to trade at black market rates, are retaining their dollars.

Ahmadinejad and his administration are bearing the brunt of the blame for the rial’s fall. Parliament voted on Sunday to consider halting further reform of Iran’s food and fuel subsidies, a centrepiece of the president’s economic platform.

Iran’s Supreme Leader, Ayatollah Ali Khamenei, has stayed above the fray, saying only that the Islamic Republic - which has also been disconcerted by the revolt convulsing Syria, its closest Arab ally - will not bow to outside pressure.