Political prisoners inside Mandalay’s Obo Prison have been beaten and put in solitary confinement for marking a key event in Myanmar’s pro-democracy struggle, according to sources.

Protests were held in the prison last week to commemorate the military’s killing of student activists and dynamiting of Yangon University’s Student Union building on July 7, 1962.

Although the protests were peaceful, consisting only of chanting poems and singing protest songs, the response was brutal, sources familiar with the situation told Myanmar Now.

“Those who organised the protests were beaten and starved,” said a member of the All Burma Federation of Student Unions (ABFSU) who spoke on condition of anonymity.

“The families of some protesters said that they were placed in solitary confinement or denied contact with anyone from outside the prison,” he added.

The exact number of prisoners affected by the crackdown was not known. Myanmar’s military junta has not commented on the situation.

Obo Prison is notorious for its treatment of inmates. Last month, two political prisoners were reportedly beaten to death and 13 others were injured amid tensions over moves to mix them with the prison’s criminal convict population.

According to a monk who attempted to deliver packages to five imprisoned clerics last Friday, the latest restrictions also appeared to apply to them.

“They wouldn’t let us in to see the detained monks. We couldn’t even hand over letters or care packages. The prison authorities only allow their relatives to visit them now,” said the monk.

However, a woman who regularly visits the prison said that even families have very limited access these days.

“You can’t meet prisoners in person right now. But I’m still able to bring care packages to my husband, perhaps because his case was not political,” she said.

“I’ve heard that it’s especially difficult for political prisoners,” she added, noting that some are limited to contact with their lawyers, who are their only sources of messages and supplies from family members.

Meanwhile, lawyers representing political prisoners have also been targeted by the junta. On June 29, three were arrested after meeting their clients at Obo Prison. It was not clear at the time what charges, if any, had been laid against them.

The previous month, prominent Mandalay lawyer Ywet Nu Aung, who represents a number of high-profile political figures, including Mandalay Region’s ousted chief minister Dr. Zaw Myint Maung, was detained on suspicions of financially supporting anti-regime armed groups.

Earlier in April, Si Thu, another Mandalay-based lawyer known for his work with farmers engaged in land disputes with the military, was beaten in front of his family before being taken into custody.

According to the Assistance Association for Political Prisoners—Myanmar, as of July 4, a total of 11,393 people detained for opposing last year’s coup remain behind bars. Of these, 1,212 have been so far handed prison sentences.