Iran's jittery regime deployed riot police at key intersections in Tehran yesterday after widespread public anger at the sudden and spectacular collapse of the country's currency boiled over into spontaneous street protests on Wednesday.
The Iranian authorities fear the economic crisis could rapidly turn more political and internecine warfare within the regime has exacerbated tensions.
Influential hardline opponents of Iran's beleaguered president, Mahmoud Ahmadinejad, maintain his incompetent and populist "Robin Hood" policies account for 80 per cent of the economy's woes.
They say draconian international sanctions imposed over Iran's nuclear programme account for just 20 per cent of Iran's economic misery.
Mr Ahmadinejad accepts no responsibility for the debacle. The currency crisis, he insists, is only "temporary". He blames international sanctions against Iran's vital oil and banking sectors, along with ruthless currency speculators. He accuses his enemies at home of joining in a "psychological war" against Iran.
Particularly alarming for the Iranian authorities was the eruption of popular fury at the grand bazaar in central Tehran where many traders closed their shops on Wednesday and joined in calls for the government to stem the economic meltdown.
The labyrinthine bazaar - the capital's commercial nerve centre - helped fund the 1979 Islamic revolution and is a critical pillar of support for the regime.
Guilds in the bazaar, however, made clear their gripe was with Mr Ahmadinejad's government and not the nezam (Iran's Islamic system), which they vowed to defend with "our lives". Most shops in the bazaar reopened yesterday and no unrest was reported. To stabilise the rial, it was assumed the government would pump dollars into the market - if it has them.
The regime, facing growing international pressure over its nuclear programme, is still haunted by the mass street protests that convulsed Iran after Mr Ahmadinejad's "stolen" re-election in June 2009. That uprising was ruthlessly crushed by security forces, leaving more than 70 dead while thousands of reformers were jailed.
Few expect a repetition of unrest on that scale now. The opposition's eviscerated Green Movement, whose two main leaders have been under house arrest since early last year, has been silent so far on the currency crisis which has seen the rial plunge by 40 per cent against the dollar this past week.
Moreover, many poorer Iranians rely on government handouts that help cushion them from the crisis and fear losing that if they protest.
Others simply fear chaos. "Looking at the violence in Syria, we do not want that they have there," one Iranian told the Tehran Bureau website.
The slogans bellowed on Tuesday were mainly economic in nature, with many calling for Mr Ahmadinejad to step down as they blamed his mismanagement for the rial's collapse. Yet while there were no calls for more democracy, some of the chants touched on highly sensitive political issues that must have hit a raw nerve in Iran's power centres.
"Leave out Syria. Think about us," some marchers chanted, referring to reports that the Iran is providing billion dollar subsidies to prop up the regime of Bashar Al Assad, Tehran's key ally. Other protesters were reported to have chanted: "We don't want nuclear energy" - a sign that some blame the parlous state of the economy on the regime's uncompromising nuclear policies, which have brought choking international sanctions.
The Iranian regime for now is delighted that Mr Ahmadinejad, who has to stand down next summer, is serving as a convenient scapegoat for the economic crisis. But his powerful opponents know that any financial instability is bad news for the regime as a whole.
The US secretary of state, Hillary Clinton, has said the Iranian government could ease its economic woes by engaging in meaningful discussions over its nuclear programme.
With the livelihoods of millions of Iranians hit by the country's worst financial crisis since the Iran-Iraq war in the 1980s, the regime in Tehran knows full well ordinary Iranians are not likely to blame their discredited president alone.
But there is one consolation for Tehran: if sanctions are supposedly biting so hard, Israel's leaders may be convinced there is no need for military strikes against Iran's nuclear facilities any time soon.