In few places is the contrast between the internet's liberating possibilities and its most troubling hazards more sharply drawn than in Pakistan.

For its burgeoning online population of 30 million people, the universal promise of the medium as a link to a world without borders comes up against a raft of local restrictions imposed on the technology itself (YouTube and a range of other sites are blocked) and its use as a tool for surveillance of the user.

The tensions are particularly acute for women, whose digital lives, at least in some parts of the country, play out against the backdrop of a conservative culture where even the fact of being online can carry a stigma.

"It's sort of fading away, but I remember when I started using the internet I wasn't allowed to use it in my home," says Nighat Dad (34), a lawyer who founded the Digital Rights Foundation (DRF) and finds herself in the vanguard of a movement working to make the internet safer for women in Pakistan.

“Even when I started practising law, the only time I could use the internet was at my workplace. It’s the social context. Mostly families, especially from the middle class, think that using social media networks is harmful for girls because they can make relationships or friendships with men, which can hurt the honour of the family.”

Online harassment is a global problem but “the consequences and the risks vary from country to country”, Dad says. To illustrate her point, she recalls a call for help she received earlier this year from two distraught young women in Peshawar.

The women said they and a number of other female students at their university were being blackmailed by someone who had set up a Facebook account containing their personal information.

The page, which first appeared in 2011, included their phone numbers, photographs and details about their personal lives along with false claims that they were prostitutes.

The perpetrators told the women they would take down the pages only if they were paid via online money transfer or if they divulged other friends’ personal information.

At first Facebook said it could not remove the pages because they were not in violation of its rules.

“These women got in touch with me and they said: ‘Some of the girls have been beaten up by their fathers, some have stopped going to university’,” Dad recalls. She contacted Facebook and within a week the pages had been taken down. Two men were later jailed in relation to the case after they were traced by Pakistan’s Federal Investigations Agency.

“It was a success, but at the same time it raises a lot of questions about platforms’ policies and how they deal with violence against women on their platforms,” Dad says. Facebook’s policy team lacked anyone who could read Pashto, the language in which the pages were written. It is essential for platforms to understand the social and cultural contexts in which they work, Dad says.

“Sometimes a post which they don’t think is violating someone’s privacy [or] they don’t deem as harassment can risk women’s lives in Pakistan.”

Such work is at the heart of Hamara Internet (Our Internet), a programme run by the DRF to teach women in the least developed parts of Pakistan about internet safety.

Dad points out that because so many women do not inform their families that they use social media, they are particularly vulnerable to harassment, intimidation or blackmail. Under the scheme, Dad and her colleagues visit colleges and other organisations, telling women about their legal rights and how they can report online abuse.

Nighat Dad is an accidental activist. When she divorced in 2007, she decided to put her law degree to use and joined a legal chambers to support herself and her six-month-old son.

Seeing so many women “sitting in corridors, helpless, waiting for their lawyers”, she gravitated to family law, in particular women’s rights. At first she began to volunteer with women’s rights organisations in her free time. Online harassment was a theme on which she was often called to give legal advice.

“That was when I started looking into different laws and policies in Pakistan [and] found there was no law on the subject . . . There was no education about how people can use it safely and securely. So that made me think I needed to do something in the digital world.”

In 2012 she founded the DRFDigital Rights Foundation, a Lahore-based outfit that carries out research and policy work and provides training for journalists, minorities and civil society groups.

Recently, its attention has been focused on fighting a draconian cybercrime Bill, which gives “blanket power” to the Pakistan Telecommunication Authority to ban any content it deems obscene, immoral, anti-army, anti-Islam or anti-state, “and we have absolutely no idea how they interpret all this terminology”, Dad says.

Pakistan already closely polices the internet. A report on internet freedom this year by US-based NGO Freedom House noted that Pakistani authorities frequently disabled internet access “during times of perceived political or religious sensitivity” and that YouTube had been completely blocked in the country since September 2012, when an anti-Islamic video sparked unrest around the Muslim world.

The report pointed to a lack of transparency about online censorship, with no published guidelines outlining why content is blocked or how to appeal.

Dad, who was in Dublin last month to address the Front Line Defenders conference of human rights activists, says she assumes her communications are being monitored. That has a chilling effect on what she says.

“I think 10 times before writing anything on Twitter or Facebook. Who is watching me? Why are they watching me? If they’re watching me, how will they interpret my message or my post on social media?”

On digital rights, Dad believes, the situation is only getting worse. Last month, a political party activist was arrested over a tweet the authorities said had breached a judge’s right to privacy – the first arrest for a tweet in Pakistan.

The Snowden leaks showed large-scale surveillance of Pakistan by the US and UK, but the revelations prompted barely a murmur of public criticism. “It didn’t make news in the major news outlets. It didn’t jolt people. Nobody raised questions of the government. To people like us, who did raise questions, the government didn’t respond.”