Almost 40 years after seeking sanctuary in Pakistan, Nusheen Bibi lives in fear of being expelled from the only country she has ever known.

Bibi was only three when her family fled the 1979 Soviet invasion of Afghanistan — some of more than 6 million Afghan refugees who crossed into neighbouring Pakistan and Iran.

They soon made a new life in northern Pakistan where Bibi grew up, got married and eventually gave birth.

But growing animosity towards Afghan refugees combined with a push from the government to repatriate thousands of Afghans has left the 40-year-old feeling vulnerable.

Under Pakistani laws, a foreign woman can acquire Pakistani citizenship by marrying a local man, but Bibi has never done the paperwork to change her nationality.

“I can't even think about leaving Pakistan,” the mother of five told the Thomson Reuters Foundation in her home, a small mud house.

“How can I leave my children, husband and entire family of in-laws?” said Bibi, who asked that her real name not be used.

Pakistan has some 1.5 million registered refugees, one of the largest such populations in the world, according to the UN refugee agency (UNHCR). More than a million others are estimated to live here unregistered.

Although repatriation is not compulsory, Islamabad has stepped up pressure to send people back and numbers have risen sharply in recent months as Afghan-Indian relations strengthened and those between India and Pakistan soured.

UNHCR said 67,057 refugees were permanently repatriated in August, up from 12,962 the month before.

In all, more than 380,000 registered Afghan refugees have returned home in 2016 so far, with more than 1.4 million still remaining in Pakistan, UNHCR said.

'Still foreigners'

In September, Pakistan extended Afghan refugees' right to stay until March 2017, but restrictions and harassment have increased, refugees and the UNHCR say.

Many Afghans complain of discrimination when considered for jobs and university places.

Pakistani officials deny there has been systematic harassment of Afghans living in Pakistan and say their country has demonstrated great generosity to the refugee population, despite severe economic problems of its own.

Like Bibi, Dilshad Begum is also facing the threat of separation from her spouse.

Begum was born in Mardan, a district of Khyber Pakhtunkhwa. In 2003, she married an Afghan man whose family migrated across the border.

But unlike foreign women, foreign men cannot acquire Pakistani citizenship through marriage.

The couple grew increasingly concerned about their future following brief clashes between Pakistani and Afghan security forces at the Torkham border crossing in June.

“My husband sold his property in Afghanistan to establish his business in Pakistan,” Begum said.

“However, the government is now asking him to close down his business, withdraw all the money from his bank and move back to Afghanistan.”

Sana, whose Afghan father moved to Pakistan at the age of eight, has tried but failed to gain a place at the University of Peshawar.

“I finished college in Peshawar, where I was born. But the management tells me the quota for Afghan students is full already, so I can't get in,” she said.

“It is extremely disturbing for me to learn that after all these years, we are still being treated as foreigners.”

Many who have returned to Afghanistan are struggling to reintegrate in a country they barely know.

Malala's family recently left for Afghanistan but the student, who declined to give her full name, decided to stay in Pakistan to complete her studies.

“I'm finding it difficult to continue because my dad is having a hard time establishing his business in Afghanistan,” she said.

But the young woman says she bears no ill will towards Pakistan.

“I was born here and love this soil. No matter where I go, Pakistan will always have a special place in my heart,” she said.