AFP

WHAT more can Iran's ruthless rulers do to squash their opponents? Since nationwide protests broke out last June over the disputed results of presidential elections, the official winner, Mahmoud Ahmadinejad, has pulled few punches. His security apparatus has beaten and arrested thousands, tried scores of dissidents in kangaroo courts, hounded others into exile, throttled the press and jammed the airwaves. But the massive and violent demonstrations that engulfed the capital, Tehran, and other cities on December 26th and 27th suggested that repression only deepens and broadens the opposition.

Footage of the protests, shot by phones and spread via the internet, revealed scenes of mayhem unprecedented since the 1979 revolution that toppled the shah. Mobs of youths, including many women, attacked and in some cases overcame squads of riot police. The rioters, mostly unmasked in contrast to previous protests, apparently chanted as many slogans against Iran's supreme leader, Ayatollah Ali Khamenei, as against Mr Ahmadinejad. They set police vehicles on fire and torched at least one police station. Plainclothes government thugs fought back, bludgeoning isolated protesters and apparently shooting several at close range.

At least eight people died in Tehran alone, including a nephew of Mir Hosein Mousavi, a former prime minister who is widely thought to have truly won the June election and who has become an opposition figurehead. Some opposition sources say the nephew was “executed” as a warning to Mr Mousavi. Kayhan, a newspaper that is a mouthpiece for regime hardliners, countered with the charge that Mr Mousavi had himself orchestrated his nephew's shooting.

The violence was particularly shocking because the protests coincided with Ashura, a solemn day in the Shia calendar that commemorates the martyrdom of Hosein, a grandson of the Prophet Muhammad. Reflecting Iran's stark polarisation, government supporters and opponents accused each other of desecrating Hosein's memory. Reflecting a fear of generating new “martyrs” to fuel further protests, security forces took over Tehran's cemeteries and nabbed the bodies of those killed, preventing their immediate burial in accordance with Muslim rites.

State news agencies say police arrested more than 1,000 protesters during the riots. Dozens more campaigners have been jailed in a dramatic widening of the purge against reformists that began in June. They include such luminaries as the 78-year-old Ebrahim Yazdi, the Islamic Republic's first foreign minister and now head of a banned liberal party, as well as numerous close relations of prominent dissidents, including a sister of Shirin Ebadi, a Nobel laureate and human-rights lawyer. This tactic has often been used in Iran to frighten prominent people, without stoking more public anger by detaining them directly. So far the authorities have refrained from arresting such figures as Mr Mousavi himself, but a new wave of arrests has swept up many of their close associates.

As in the past, conservatives have blamed foreign powers for stirring up the protests. Yet with the clashes persisting despite Iran's isolation from the outside world, this charge is carrying ever less weight with the people. On the contrary, the government's tactics, along with Mr Khamenei's silence and the increasingly ungloved intervention of the Revolutionary Guards, the elite military corps that commands the plain-clothes baseej militia used for crowd control, may reflect a growing sense of desperation.

Signs of the regime's fading legitimacy are numerous. In December, for instance, the head of Iran's central bank issued a stern warning that from January 8th it would no longer accept bank notes defaced by extra words. In practice, this would mean taking millions of notes out of circulation, following a quiet campaign by oppositionists to mark them with anti-regime slogans.

More embarrassing still for a regime that describes itself as Islamic is the government's treatment of dissident clerics, including some prominent ayatollahs. The most senior was Grand Ayatollah Hosein Ali Montazeri, a confidant of the Islamic Republic's founding father, Ayatollah Ruhollah Khomeini, with whom he fell out of favour shortly before the old man's death in 1989. Placed under house arrest for a decade, Mr Montazeri continued to criticise the government, siding openly with the reformists after the tainted June elections.

Despite his isolation, Mr Montazeri remained popular, so his death on December 20th was yet another occasion for protest. Rather than risk demonstrations, the government saturated his official funeral with baseej agents and banned memorial rites elsewhere, sparking clashes in several cities. In recent days baseej forces have surrounded the homes of two other prominent dissident ayatollahs in a blunt effort to block them from becoming a focus for protest.

Perhaps worse yet for Iran's government, its troubles at home have crippled its foreign policy, at a time when it faces rising pressure to curb its controversial nuclear programme. Western countries that had shied from too strong a condemnation of Iran's human-rights record, for fear of empowering the more extreme nationalists and threatening nuclear diplomacy, are losing patience. Even the pragmatists among Iran's friends, such as Russia and China, now fear their longer-term and potentially lucrative interests in Iran may be hurt by too close an embrace of the regime. If they refuse to vote against tougher sanctions expected to be proposed soon against Iran at the UN Security Council, even Messrs Ahmadinejad and Khamenei may start to fear that their days in power may be numbered.