Islamabad, Pakistan - Pakistan's government has extended a deadline for Afghan refugees to leave the country until the end of 2017, according to state media.

A meeting of the cabinet, presided over by Prime Minister Nawaz Sharif, on Tuesday pushed back the refugees' legal right to stay from the previous deadline of March 31, state-run APP news agency reported.

There are currently about 1.3 million registered Afghan refugees residing in Pakistan, according to the United Nations High Commission for Refugees (UNHCR).

Many fled violence in their country more than 30 years ago, during the Soviet invasion of Afghanistan, with others fleeing the US-led invasion in 2001.

There are also about a million unregistered Afghan refugees present in the country, Pakistani officials say.

A recent crackdown by Pakistani authorities, citing security concerns, has seen a sharp rise in both deportations and voluntary repatriations of Afghan nationals from the country.

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Last year, more than 600,000 Afghan refugees left Pakistan to return to their home countries, data from the UNHCR and the International Organization for Migration (IOM) shows.

For registered refugees, that number represents a more than six-fold increase from the previous year, according to UNHCR.

At least 22,559 Afghans were also deported by Pakistani authorities in that period, IOM says.

Refugees and rights groups say increased harassment by police and stricter restrictions on crossing and returning from Pakistan's northwestern border with Afghanistan have been responsible for the rising numbers.

The cabinet meeting on Tuesday reaffirmed those tighter controls on the border.

"It was also decided that the Afghans cross-border movement would now be regulated through the visa regime and their entry passes would be linked with it," reported APP.

In November 2015, US-based rights group Human Rights Watch documented a campaign of abuse and harassment of Afghan refugees by Pakistani police, involving confiscation of their registration cards, bribes and raids on their homes.

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Pakistani officials deny there is any such policy or campaign.

Until last year, Pakistan regularly extended the Afghan refugees' legal status in the country for at least 12 months every year. In June, however, an extension of only six months was offered until December 31, 2016.

The next extension lasted only three months, until March 31, 2017.