Tension was visible as the MQM, the single largest party in the country's biggest city Karachi, announced the strike after a long break in its protests that usually bring life to a halt.
The move was announced at a news conference at MQM headquarters by senior party leader Haider Abbas Rizvi.
Rizvi said his party was losing patience as the writ of law was not being followed and MQM workers were being targeted by law enforcement and security agencies.
"Noman was later dropped off the next day; however, the mutilated body of Salman was recovered from Shah Latif Town," Haider said.
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He alleged that the MQM activist was subjected to horrific torture and presented some photos of Salman as evidence.
Haider said under the garb of an operation against criminals and militants in the city, paramilitary troops and police were carrying out a targeted drive against MQM workers.
He claimed more than 40 MQM workers had disappeared since the operation began in November. "We don't know their whereabouts and whether they are dead or alive," he said.