Seda-ye Edalat (The Voice of Justice) said the sentences were handed down in the western city of Hamedan. The teachers were arrested during the Iranian month starting in late March, when the newspaper said they spent nine days in solitary confinement.
Some teachers have staged protests in Tehran and elsewhere over the past year demanding better pay and conditions. Many of them make the equivalent of a few hundred U.S. dollars per month and have seen their real wages eroded by double-digit inflation.
It was unclear whether the teachers had served part of their sentences. Officials were not available for comment.
Iranian Education Minister Mahmoud Farshidi resigned on Dec. 2 in a move analysts said might have been linked to his unpopularity with teachers, making him a potential liability for the government ahead of the March parliamentary election.
Western governments and human rights groups have accused the Islamic Republic, under international pressure over its nuclear programme, of taking a tougher line on dissent in general.
Iran routinely dismisses accusations of rights violations and says it is acting on the basis of Islamic sharia law.
In a case that has sparked concern among rights campaigners, an Iranian judge was quoted as saying two women arrested in a Kurdish region a few months ago were accused of being members of a rebel group and of involvement in bombings.
U.S.-based Human Rights Watch last month said the activists Ronak Safarzadeh and Hana Abdi, both 21, were detained in the northwestern city of Sanandaj in Kurdistan province.
It said they were active in a drive to collect one million signatures in favour of greater female rights. Campaigners say Iran discriminates against women, a charge Tehran denies.
The unnamed judge said “anti-revolutionary groups use civil organisations to cover up their terrorist activities,” the official IRNA news agency reported on Sunday.
“They have been accused of acting against national security, by participating in bombing cases in Sanandaj and being members of PJAK,” the judge was quoted as saying.
The Party of Free Life of Kurdistan (PJAK) is an Iranian offshoot of the separatist Kurdish Workers Party (PKK) movement that is fighting neighbouring Turkey.
Several clashes between Iranian forces and Kurdish rebels have been reported this year in northwest Iran.
