Ethnic Hazara women in the Pakistani city of Quetta are refusing to bury the bodies of scores of people killed by a huge bomb in a Shia commercial area.
Shia Muslim Hazaras are furious at what they see as a lack of protection from local and national forces, in the face of repeated attacks.
Saturday's bomb ripped through a busy market district, killing at least 84 and injuring some 169 people.
The huge attack - the second this year - was carried out by Sunni militants.
As many as 4,000 women began a sit-in in Quetta, in south-west Pakistan, on Sunday evening.
The blocked a road and refused to carry out the traditional ritual of burying the Hazara dead until action was taken against the bombers, the AFP news agency reported.
One local Shia leader, Qayyum Changezi, told AFP the protesters "will not bury the dead until a targeted operation is launched".
Reports said thousands of angry Hazaras moved the bodies to a local mosque but then began chanting and protesting instead of proceeding with the burials.
Strikes and protests were reported elsewhere in the country as well, including the commercial capital Karachi.
Sunni militant group Laskhar-e-Jhangvi said it had carried out the bombing, which hit a largely Hazara area of Quetta.
The attack was the second highly destructive bombing in Quetta in the space of a month. In January bombers targeted a snooker hall in the city, killing some 90 people.
Another bomb at a Shia mosque earlier in February killed 24 people, raising the Shia death toll to more than 200 in less than two months of 2013, according to reports.
On Sunday, Balochistan Governor Nawab Zulfikar Magsi - given greater powers after the recent blasts - said local security forces were either "too scared or too clueless" to act.
He said he had given security forces a "free hand" to take action against extremist groups, but that this had clearly failed.
He said: "It's their job to pre-empt such attacks. That's what they are paid for."
BBC Afghan's Imran Ali says the inaction has come as no surprise to the Hazara community, and frequent targeted killings and bomb explosions in Quetta mean many Hazaras are living in a state of fear.
Many are apprehensive to leave their homes and those who work in areas that are deemed dangerous are told by their employers to stay at home, our reporter adds.
Quetta is the capital of Balochistan province, which borders Iran and Afghanistan, and has been plagued by a separatist rebellion as well as sectarian violence.
Hundreds of Shia Hazaras in Quetta have been killed in attacks over the past few years.