A hard Brexit would send the quality of British citizenship into a "free fall", comparable to the effects of warfare on Syrian and Libyan nationalities, a new report shows.

Results of the second Henley & Partners - Kochenov Quality of Nationality Index (QNI) have shown that the global standing of UK citizenship would suffer significantly if free movement was scrapped, robbing Brits of the right to work and settle in countries across the European Union.

Britain currently falls outside of the top 10 ranking, but a hard Brexit would leave the UK in a far less enviable position, "overwhelmingly impairing the quality of its nationality", it said.

The report explained: "Even if you presume no economic loss to the UK as a result of leaving the EU and focus only on the external rather than internal components of nationality quality, the UK will be in a free fall in terms of its quality, losing its value very sharply and by far exceeding the losses experienced by the countries in the midst of bitter political and armed conflicts, as well as divided societies whose nationalities are at the forefront of failing to perform, such as the Syrian and Libyan nationalities."

The UK currently ranks 11th in the QNI Index (PA)

The index ranks the value of every nationality worldwide, based on measures including quality of life, mobility, limitations and global opportunities "inherent" in their passports. It then divides nationalities into five tiers, from "extremely high quality" through to "low quality" status.

The UK currently ranks 11th out of the 28 countries in the "extremely high quality quality" category, requiring a score of 75% or above, out of 100%. It already falls behind the likes of Germany, France, Denmark and Iceland as the most valued global nationalities.

Germany came out on top with a score of 82.7% out of a possible 100%, while Afghanistan ranked lowest with a score of 14.6%.

Commenting on the risks to the UK, Dimitry Kochenov, a constitutional law professor and creator of the QNI index, said: "The moral is simple: EU citizenship is an extremely valuable resource and getting rid of it - crippling citizens' horizon of opportunities - should not be taken lightly."