Pakistan has adopted a much-criticised cyber security law that grants sweeping powers to regulators to block private information they deem illegal.

The National Assembly approved the Prevention of Electronic Crimes Bill 2015 late on Thursday after the Senate had unanimously adopted it last month.

Government officials say internet restrictions under the new law are needed to ensure security against growing threats, such as terrorism.

But the law has alarmed human rights and pro-democracy activists worried that its vague language could lead to curtailment of free speech and unfair prosecutions.

"The overly broad language used in the bill ensures that innocent and ignorant Pakistani citizens, unaware of the ramifications of what the bill entails, can be ensnared and find themselves subject to very harsh penalties," said Nighat Daad, founder of a group called the Digital Rights Foundation.

"There have been no provisions set in place to protect sensitive data of Pakistani users. The state cannot police people's lives in this manner."

The law provides for up to seven years in prison for "recruiting, funding and planning of terrorism" online.

It also allows "authorised officers" to require anyone to unlock any computer, mobile phone or other device during an investigation.

Activists say the bill's vague language without well-defined descriptions for libel or defamation typical in other countries' could be used to prosecute any satirical website, including political ones.

The law also carries a penalty of three years for "spoofing".

"Whoever with dishonest intention establishes a website or sends any information with a counterfeit source intended to be believed by the recipient or visitor of the website, to be an authentic source commits spoofing," the law says.

Daad said the bill allowed the Pakistan Telecommunications Authority "unlimited powers" to decide what was illegal.

Governments around the world have been grappling with how to block online incitement to criminal activity, while major internet services have stepped up campaigns to identify and remove Web postings that incite violence.

Facebook, Google and Twitter are working more aggressively to combat online propaganda and recruiting by Islamist militants while trying to avoid the perception they are helping state authorities police the Web.

More than 30 million of Pakistan's 190 million people use the internet, mainly on mobile telephones, according to digital rights organisation Bytes for All.Governments around the world have been grappling with how to block online incitement to criminal activity, while major internet services have stepped up campaigns to identify and remove Web postings that incite violence.

Facebook, Google and Twitter are working more aggressively to combat online propaganda and recruiting by Islamist militants while trying to avoid the perception they are helping state authorities police the Web.

More than 30 million of Pakistan's 190 million people use the internet, mainly on mobile telephones, according to digital rights organization Bytes for All.