Thousands of Iranian workers on Monday lambasted the growing use of short-term employment contracts in the most vociferous May Day demonstration in the Islamic state for years.
The protest came as a reminder to President Mahmoud Ahmadinejad that, although embroiled in an international dispute over his country's atomic ambitions, he was elected to improve living conditions for the poorest echelons of society.
Short-term contracts, while better paid than regular staff contracts, allow bosses to sack workers more easily and cheaply.
"The contract worker is a slave as he lives in fear of being sacked," said Aliasghar Ghaliaf, 37, who has worked in a textile factory on a permanent contract for 19 years.
"Employers set us up against the contract workers, accusing us of not working hard enough," he added. Paper-factory worker Masoud Cheraghi, 40, said: "Some employers even make contract workers sign a resignation form without a date on it."
The demonstrators, numbering some 10,000, called for Labour Minister Mohammad Jahromi to resign and brandished placards with bread stuck on them to symbolise their hand-to-mouth existence.
Some wore headbands saying: "The short-term contract is a slavery law". Other carried banners that read: "Labour strikes must be revived".
The protesters spread out for more than a kilometre, beating their chests in emulation of religious mourning ceremonies.
Unions exist in Iran but their power is limited. Authorities quickly snuff out strikes and protests over living conditions.
THREAT TO JOB SECURITY: Short-term contracts were introduced by the previous administration of pro-reform cleric Mohammad Khatami as part of attempts to make the state-heavy economy more efficient.
The Labour Ministry said it was looking at ways to "optimise" the contracts in favour of workers.
The Labour House, the largest labour foundation in Iran, said temporary contracts were a threat to job security.
"This is an idea that sacrifices the rights of the workforce on the pretext of boosting investment and profits," said the Labour House's legal adviser Arash Faraz.
Iran's government says 10.9 percent of the workforce is unemployed, but some economic analysts say the real figure could be nearer 25 percent.