Thousands of teachers across Iran have taken to the streets again, urging the release of their fellow teachers who were detained in previous protests.

The nationwide protests, which was called by the Coordination Council of Iranian Teachers’ Trade Associations, started Thursday morning in 120 cities and towns all over Iran.

The teachers gathered in front of the parliament building in Tehran and the provincial offices of the education ministry to protest the parliament’s adoption of a discriminatory ranking plan.

Videos on social media show large crowds of protesters shouting slogans against the relevant authorities asking their resignation.

In many cities the rallies were held in a peaceful atmosphere while security forces and officials were present to prevent any anti-regime slogans, but some scuffles were also reported in Tehran and Shiraz where the demos continued to midafternoon.

According to reports, the prosecutor's office of the Fars province had sent a text message to people in the province, threatening them to stay away from Thursday’s protests.

Police often respond with heavy-handed tactics since protests have gained momentum all over Iran. Several teachers have been arrested during the rallies.

Education International and its member organizations have urged Iran to allow teachers protest for fair pay and to release those jailed.