A YEAR ago last Saturday, Ali Khamenei ordered the abduction of trade-union leader Mansour Osanloo. In so doing, Iran's top ruling mullah hoped to kill in infancy the independent trade-union movement that Osanloo had launched in '05 with the help of colleagues among bus drivers and conductors in Tehran.

A year later, Osanloo is still in prison, sentenced to five years on a charge of "undermining the security of the Islamic Republic." Yet the free-union movement that he inspired has spread like wildfire.

Transport workers in Tehran and its suburbs have refused to disband their union and rejected the mullahs that Khamenei appointed as their leaders.

Workers in the auto, construction and petrochemical industries have set up their own independent unions, as have teachers, miners, dock workers and bakers. The Workers Organizations and Activists' Coordination Council, an umbrella group for the free unions, now boasts more than 700 groups across Iran with almost 2 million members.

Earlier this month, the 6,000 workers of the Haft-Tapeh sugar plantation and refinery, the Middle East's largest, announced their own independent union after a year of strikes and demonstrations that led to violent clashes with security forces and the arrest of 20 trade unionists.

Osanloo is kept in the dreaded Evin Prison, where the Islamist regime locks up those it fears most. In a statement relayed by his family, he accused the authorities of "systematic mistreatment, insult and abuse." Suffering from an eye infection and a heart condition, the union hero isn't permitted proper medical care.

Despite "intense psychological pressure and physical hardship," he has refused to call for a dissolution of independent unions and a return to mullah-controlled "Islamic labor associations."

Labor is fast emerging as the biggest threat to the mullahs' rule.

Over the last year, the country has witnessed hundreds of strikes, including some involving tens of thousands of workers. The regime has responded with brutal repression, organizing armed thugs known as Ansar Hezbollah (Supporters of Hezbollah) to break strikes, beat up strikers and abduct trade unionists.

In the latest incident, Hezbollah gangs in April attacked striking workers at the Kiyan Tire Factory at Char-Dangeh with electrical batons, injuring dozens and abducting more than 100.

WOACC has also reported at least 20 "suspicious deaths" over the last year, workers believed to be victims of Hezbollah killers. The Ministry of Islamic Labor has classified the deaths as "work-site incidents."

No one knows quite how many workers are under arrest; WOACC estimates 4,000-plus. Thousands more are picked up for a few hours or a few days, beaten, bullied, warned and released. "Every day, millions of people go to work in Islamic Iran in a state of fear," says a WOACC activist. "Basically, terror is the principal instrument of social control in this country."

The regime isn't relying on violence alone to crush the workers' movement. President Mahmoud Ahmadinejad has presented legislation to abolish most rights won by Iranian workers over the last 100 years. The reasoning is a claim that Islam doesn't recognize a division of the community of the faithful into employer and employee and rejects international labor codes "invented by Zionists and Crusaders."

Ahmadinejad's administration has also lifted most legal limits on "contract work."

Rajab-Ali Shahsavari, an independent unionist and leader of the Association of Contractual Workers, reports that more than 85 percent of private-sector workers now labor on short-term contracts lasting just a day to a month. "This is slavery in the name of Islam," Shahsavari says. "In Iran today, workers are worse off than slaves in ancient times."

The regime also is trying to isolate the labor movement by accusing some of its leaders of hidden ethnic or ideological agendas. For example, it has accused Mahmoud Salehi, the popular imprisoned union leader in Kurdistan province, of being "a closet Communist" and a "Kurdish secessionist." These charges are so ridiculous that it hasn't dared actually bring them - even in the mock trial it organized against him.

Sadly, the struggle of Iran's workers against one of the world's most evil regimes has yet to receive the attention it deserves from the major democracies, including the United States. With one or two exceptions (including The Post), the US media seem to have ignored what could be the biggest story in Iran.

Amir Taheri's next book, "The Persian Night: Iran Under the Khomeinist Revolution," is due out this fall.