Pakistan has banned the Pashtun Tahaffuz Movement (PTM), or Pashtun Protection Movement, a prominent rights group, listing it as a “proscribed organisation”.

A notification issued by the federal government on Sunday said the PTM was “engaged in certain activities which are prejudicial to the peace and security of the country”.

Pashtuns are a distinct ethnic group with their own Pashto language, living mostly in Pakistan and Afghanistan but divided by the colonial-drawn Durand Line that splits the two countries.

The movement, founded in 2014, advocates for the rights of ethnic Pashtuns affected by Pakistan’s war against the Taliban and its local affiliate, Pakistan Taliban, known by the acronym TTP.

PTM is known for its strident criticism of Pakistan’s powerful military for its role in alleged enforced disappearances and extrajudicial killings of rights activists and ethnic leaders.

PTM, which is not a political party, has at its peak pulled tens of thousands of people to largely peaceful rallies demanding better protection from the state. It said more than 200 activists have been arrested in recent days in advance of a jirga, or a council of elders, planned for later this week.

Pakistani authorities have in recent months attempted to curtail dissent – clamping down on the street power of jailed opposition leader and former Prime Minister Imran Khan after he led a wave of criticism against the powerful military and intelligence services.

At the weekend, the capital was on lockdown with entry and exit points blocked and mobile phone services cut as Khan supporters attempted to protest. The demonstrations came weeks after the government introduced a new protest law that limits gatherings.