Charities have warned of a global "knock-on effect" if Donald Trump goes ahead with a temporary ban on refugees entering the US, as the withdrawal of American leadership on refugee action creates a “vacuum of leadership”.

The President is expected to announce a 120-day ban by way of an executive order later on Thursday in a move that has prompted "extreme alarm" among refugee advocates, who are asking him to reconsider.

Mr Trump is also expected to ban immigration and the issuing of visas for people from seven Muslim-majority Middle Eastern and African countries.

The US resettles more refugees than any other country, according to the NGOs, taking in two thirds of resettlements in the world in 2015.

Humanitarians have expressed fears that a sudden lack of US leadership could have disastrous impacts on the protection of refugees.

“President Trump’s plans to pull up the drawbridge and leave refugees trapped in danger are extremely alarming,” the British Refugee Council’s Anna Musgrave told The Independent.

“We can’t let our humanity be undermined by fear. We all know that refugees who arrive in the US through resettlement schemes are among the most rigorously vetted people in the country.

“What’s even more disturbing is the fact that the US currently resettles more refugees than any other country in the world and has led the way in coordinating a global effort to ensure more refugees are able to find safety.”

The Council voiced concerns about the world-wide "knock on effect" Mr Trump’s actions would have and particularly the example it would set.

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Ms Musgrave said: "Global leaders must lead by example by offering safe haven, rather than turning their backs on refugees and leaving the job to others.

“With this new vacuum in leadership it’s vital that other countries, including Britain, step forward and ensure that men women and children who are running for their lives are offered safe haven.”

The International Rescue Committee (IRC) is the main organisation working to resettle refugees within the US.

David Miliband, President of the IRC and former UK Foreign Secretary, said: "The IRC is very concerned by the reports of new restrictions on refugee resettlement into the US and calls on the administration to take its time and think again.

"Refugee resettlement is an American success story. For decades people have looked to the US as a beacon of political as well as religious freedom. The IRC is proud to have resettled 400,000 refugees into the US since World War II."

Turkey's two million Syrian refugees Show all 11 1 /11 Turkey's two million Syrian refugees Turkey's two million Syrian refugees There are already over 2.5 million Syrian refugees in Turkey, but their current camps can only hold 200,000 people ADEM ALTAN/AFP/Getty Images Turkey's two million Syrian refugees Turkish citizens protest a new deal, also criticised by human rights activists, which will see refugees who arrived in Greece after March 20 be sent back to Turkey AP Photo/Emre Tazegu Turkey's two million Syrian refugees An estimated 80% of Syrian refugee children already in Turkey are unable to attend school BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Refugee children beg for water near the Turkey-Syria border. Turkey has been accused of illegally deporting asylum-seekers back to Syria BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees In Turkey, no-one from outside Europe is legally recognised as a refugee, meaning the 2016 deportations may not meet international legal standards for protecting vulnerable people BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees A refugee child cries as she is searched by police at the Syria-Turkey border, where 16 refugees (including three children) have been shot dead in the last four months BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Many refugees are living rough on the streets of cities such as Istanbul or Ankara (pictured) ADEM ALTAN/AFP/Getty Images Turkey's two million Syrian refugees Turkish soldiers use water cannon on Syrian refugees BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Syrian refugees shelter from rain in the streets of Istanbul BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees A derelict building housing Syrian refugees in Istanbul Carl Court/Getty Images Turkey's two million Syrian refugees Turkey houses around half of all the refugees who have currently fled Syria Carl Court/Getty Images

Citing record-breaking levels of refugee flow around the world, Mr Miliband said now was "not the time" for America to renounce its historic leadership role.

"Our clear message to the new administration is: now is no time for hasty action," he added. "Talk to us and the experts in your own government to develop a policy that builds on America’s success rather than undermines it."

Another organisation, Help Refugees, warned of the “devastating” impact if the US becomes closed off to refugees.

A statement released by the charity said: “Refugees are, by definition, people seeking sanctuary from some of the most horrific circumstances and it is the duty of compassionate and progressive nations to accept their fair share. Banning refugees on the basis of their religious beliefs is abhorrent.

“Halting resettlement of refugees will not, contrary to Trump's assertions, make America safer. On the contrary it will force people into the hands of traffickers and make the vigorous systems currently in place to vet refugees entering the US completely defunct.”

Among many others, Mr Trump's executive order threatens a refugee resettlement deal with Australia signed late last year, and could leave more than 1,000 asylum seekers in limbo.

"We already didn't have much hope the US would accept us," Behrouz Boochani, an Iranian refugee who has spent more than three years on Manus island, told Reuters. "If they do not take us, Australia will have to."

The US agreed to resettle an unspecified number of refugees being held in Papua New Guinea and the tiny South Pacific island nation of Nauru on Australia’s behalf, under a deal to be administered by the UN refugee agency.

"Any substantial delay in the relocation of refugees...would be highly concerning from a humanitarian perspective," said Catherine Stubberfield, a spokeswoman of the UN High Commissioner for Refugees.