After a deadly clash between troops and activists at a security post in northern Pakistan, organizers of a rights movement that has unnerved the powerful army say a campaign of intimidation against them has intensified, with many top leaders detained.

The military denies a crackdown against the Pashtun Tahaffuz Movement (PTM), which campaigns against alleged extrajudicial killings and enforced disappearances of Pashtuns and other ethnic minorities, but says it is acting against lawbreakers.

Manzoor Pashteen, the PTM's charismatic figurehead, said he has seen his closest aides detained. Two lawmakers who are part of the group's leadership have also been arrested.