The United Nations voiced concern Thursday over allegations of "very grave" rights violations and forced disappearances during Pakistani military operations against insurgents and militants. Independent watchdogs have accused Pakistani security forces of mass arrests and extra-judicial killings in the southwestern province of Baluchistan, where a separatist insurgency began in the resource-rich region in 2004. "I am concerned by allegations of very grave violations in the context of counter-terrorist and counter-insurgency operations," UN human rights chief Navi Pillay told a press conference at the end of a four-day visit to Pakistan. "These include extrajudicial killings, unacknowledged detention and enforced disappearances." She said disappearances in Baluchistan had become "a focus for national debate, international attention and local despair" and urged the government and judiciary to investigate and resolve the cases. She said she regretted not visiting Baluchistan and the southern province Sindh, where hundreds of people have been killed in political and ethnic clashes in Karachi this year, without explaining why she had not gone. "I called for investigations of all this and compensation for victims and of course I am very concerned about what steps can be taken to protect people from these kinds of attacks," she said.