The chance of a being killed by a refugee terrorist in the US is one in 3.64 billion, according to a new report that studied the tangible risk posed by immigration.

The statistic was revealed as news emerged of President Donald Trump's plan to issue an executive order suspending immigration from seven Muslim-majority countries, and ban refugees from entering the US for 120 days.

The draft order, is reportedly titled "Protecting the Nation From Terrorist Attacks by Foreign Nationals" and includes plans to suspend applications from Syrian refugees indefinitely, according to the political website, Vox.

The new US leader repeatedly championed the policy during his presidential campaign, arguing that it would protect American people from the threat of terrorism.

However, a Cato Institute study, “Terrorism and Immigration: A Risk Analysis”, found little evidence to suggest this would be an effective policy.

The report said the chance of being killed by a terrorist attack perpetrated by an illegal immigrant was one in 10.9 billion per year.

The chance of being murdered by a tourist on the common B visa was 1 in 3.9 million per year, it added.

Critics called the Republican leader's proposed measures "unjustifiable", and a spokesperson for the UN High Commissioner for Refugees called the plans "highly concerning from a humanitarian perspective".

Dr Richard Johnson from the University of Oxford’s department of politics told The Independent: “He is seeking to introduce this policy on a country-wide basis because he cannot actually fulfil what he said he wanted to do during his campaign, which was to ban all Muslims in the US.

“This is an ineffective and unjustifiable policy in terms of what it's trying to achieve - if it's a security measure then it seems a pretty broad brush one. Some of the most recent attacks in the US have been people born there or who have lived in the country for some time.”

International Rescue Committee president David Miliband called on Mr Trump to rethink the proposed restrictions.

"We are very concerned by the reports of new restrictions on refugee resettlement into the US and call on the Administration to take its time and think again. Refugee resettlement is an American success story," he told The Independent.

"At a time of record-breaking levels of refugee flow around the world, now is 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."

Mr Trump has denied the policy would be a “Muslim ban” but that it would instead constitute “extreme vetting” of certain nations.

“You’re looking at people that come in in many cases with evil intentions. I don’t want that. They’re ISIS. They’re coming in under false pretence. I don’t want that," he said during an interview on ABC.