Attackers have used elaborate schemes to steal data and install spyware on Pakistani activists' electronic devices, the watchdog said in a report.
The study - entitled "Human Rights Under Surveillance" - is based on the experience of four activists out of a dozen cases investigated by Amnesty, the report's co-author Sherif Elsayed-Ali told AFP.
One campaigner, Diep Saeeda, said she suffered sustained harassment by hackers after calling for the release of activist Raza Khan , who fellow campaigners say was abducted from Lahore in December. Saeeda told Amnesty that after she started campaigning for Khan's release, she was lured by a hacker posing as an activist on Facebook into revealing her email address.
She was then sent emails disguised as messages from government departments containing malicious links aimed at stealing her passwords and data.
"Every time I open an email I am now scared. It's getting so bad I am actually not able to carry out my work," Saeeda told the organisation.
Amnesty documented a series of similar methods used to try to contaminate activists' computers and phones with malicious software, some of which was created by "a network of individuals and companies based in Pakistan".
The watchdog said it was unable to identify the entity orchestrating the attacks, but demanded that Pakistani authorities order an "independent and effective" probe. "It is already extremely dangerous to be a human rights defender in Pakistan and it is alarming to see how attacks on their work are moving online," said Elsayed-Ali in a statement.