As chemical attacks continue across schools in Iran, threatening text messages from Iran's security agencies have been sent to teachers warning them from supporting protests.

Teachers and activists who organized gatherings and protests to express concern over the health of students, were also summoned by the judicial authorities.

During Tuesday's nationwide protests against the serial poisonings, the law enforcement forces violently attacked teachers and parents in different cities by firing tear gas while several were arrested.

At least 297 poisonings have been reported in girls' schools in 25 Iranian provinces since November 30when the first attack occurred in the religious city of Qom, believed to be led by regime agents in a bid to quash students' support of the 'woman, life, freedom' movement.

The chemical attacks were not limited to schools, and in the past days, female students at university dormitories have also been targeted. Nearly two thousand students have been taken to hospitals and medical centers so far.

Meanwhile, summonses and sentences for civil, political and student activists continue. In a recent case, a revolutionary court sentenced children’s rights activist Samaneh Asghari to 18 years and three months in prison, of which six years and three months can be enforced.

Samaneh Asghari, an industrial engineering student at Kharazmi University, was arrested on October 19 during a protest in Tehran.

Leila Hosseinzadeh, a political activist, and student has also tweeted that she has been summoned by the ministry of intelligence.