Human Rights Watch has accused the Jordanian government of summarily deporting hundreds of registered Syrian refugees, despite the possible harm they may face by going back to their war-torn country.

"Jordanian authorities have been summarily deporting Syrian refugees - including collective expulsions of large families," HRW said in the report.

The US-based rights advocacy group released a 27-page document that chronicled the deportation of 400 refugees during the first five months of 2017. It has also called on other countries to increase their assistance to Jordan, which has hosted more than 650,000 Syrian refugees.

"Jordan shouldn't be sending people back to Syria without making sure they wouldn't face a real risk of torture or serious harm and unless they have had a fair opportunity to plead their case for protection," said Bill Frelick, refugee rights director at HRW.

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The rights group also accused Jordan of violating its obligations under the Arab Charter of Human Rights, to which it is a party.

According to the report, some 300 registered refugees returned to Syria voluntarily during that time, and another 500 returned under "unclear" circumstances.

Since the beginning of the Syrian civil war that is now in its seventh year, Jordan has hosted hundreds of thousands of Syrian refugees, according to the UN.

But the Jordanian authorities have placed the number at more than one million people.

The report includes testimonies of 35 Syrian refugees in Jordan, and 13 others who have recently been deported to Syria.

Those interviewed say the Jordanian authorities provided little evidence of misconduct before forcefully deporting them, and claim that they were not given the opportunity to appeal or seek legal assistance.

Refugees left stranded

Last year, at least six Jordanian soldiers were killed in an attack near the country's border with Syria, in the northeast Rukban district.

Following the incident, the Jordanian army declared the northern and northeastern border with Syria as closed military zones.

As a result, some 50,000 refugees were left stranded in remote border areas, with limited access to food, water and humanitarian aid.

Ahmed Benchemsi, HRW's advocacy and communications director of the MENA division, told Al Jazeera that the Jordanian authorities cite security reasons as the basis of these deportations.

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Since the expulsion of Syrian refugees coincides with attacks on Jordanian security forces, the authorities have not provided "direct links with these people to the attacks," said Benchemsi.

"It [expulsions] should not be done in an arbitrary manner."

HRW reached out the Jordanian authorities for explanation in August, but did not receive a response, said Benchemsi.

"We believe it is somehow linked to the attacks against Jordanian forces. This is what local aid workers tell us," he said.

Mohammad Momani, Jordan's minister of state for media affairs, rejected HRW's findings.

"The return of refugees is voluntary and not to any dangerous areas," he told local news media.

According to local media, he also said international organisations should do more to pressure other countries to host more refugees.

'Minor violations'

Though Jordanian authorities regularly cite security concerns as reasons behind deportations and border closures, local rights group say that deportation orders can come from more than one institution in Jordan.

"Sometimes, minor violations can trigger deportations," Essa Al Mazareeq, head of the Syrian refugee team at the Amman-based National Center for Human Rights, told Al Jazeera.

"Orders can come from the ministry of labour, the ministry of foreign affairs, or from the public prosecutor's office - all for different reasons," he explained. "But decisions based on security issues will always be above us."

According to Al Mazareeq, though not formally announced, Jordan's borders with Syria remain largely closed-off, with authorities only granting a limited number of people entry to the country.