Former Pakistan PM Imran Khan on Wednesday said senior leaders of his party PTI were being pressurised to resign.
The ousted PM Imran Khan’s reaction came after senior leader of his party and former cabinet minister resign from his party.
According to the rights groups, quoted by news agency PTI, the authorities have detained thousands of supporters of Khan's Pakistan Tehreek-e-Insaf (PTI) party since days of street violence erupted over his brief arrest earlier this month.
“Party spokesman Fawad Chaudhry, who served as information minister in Khan's government, quit the party while general secretary Asad Umar, the former finance minister, said he would step down from his position but remain with PTI,” the report said.
It came after senior vice-president Shireen Mazari parted ways with Khan on Tuesday.
All three made their announcements after being released from custody on allegations of instigating street violence after Khan's arrest.
"This is a crackdown that I have never seen in the history of Pakistan before," Khan said in a video address on Wednesday night.
If you say that you are part of PTI, then you will face oppression and violence, you will be locked up," he said.
"If you say the magic words, 'We are no longer in PTI', then you will be released."
Khan claimed the suppression was being targeted at grassroots supporters, as well as officials.
"They have put everyone in jail, I don't even know who to contact anymore," he said from his home in the eastern city of Lahore.
Chaudhry announced his resignation on Twitter, denouncing the civil unrest and saying he would "take a break from politics".
Umar meanwhile held a press conference, saying he had not been pressured into the decision to step down as general secretary.
Amnesty International on Tuesday said "a pall of fear hangs over Khan's supporters following the arbitrary arrests of many opposition leaders".
"Authorities must stop clamping down on the political opposition" they said in a joint statement with other organisations, accusing the government of using "vague anti-terrorism laws" to justify detentions.
Since he was ousted from office, 70-year-old Khan has waged an unprecedented campaign of defiance against the powerful military establishment, long regarded as Pakistan's powerbrokers.
He accuses the top brass of orchestrating his downfall and even plotting a November assassination attempt in which he was shot in the leg, allegations that the army denies.
His arrest on graft charges at the Islamabad High Court came just hours after he repeated the claim and was seen by his party as a bid to quash support ahead of elections due no later than October.
People rampaged through cities, setting fire to buildings, blocking roads and clashing with police outside military installations during unrest in which nine people were killed.
Khan walked free from three days of custody after the Supreme Court declared the arrest illegal.
The military has denied claims by Khan that "agencies" planned the violence to smear his party.
Meanwhile Islamabad has pledged to try in military courts those accused of violence against army installations.
(With PTI inputs)