According to lawyers with the UN refugee agency, Rwanda’s asylum system is so poor that it biases against many people who could be genuine refugees.

During the second day of the UK government’s appeal over its controversial plan to send some asylum seekers to the African country, the warning was issued.

In June, the Court of Appeal ruled that the scheme was unlawful.

However, ministers say it meets the legal test for treating people humanely.

In a 16-month battle over the government’s plan to send some small boat migrants to Rwanda, the UN Refugee Agency (UNHCR) has played an increasingly crucial role in determining whether it meets a complex legal test.

While Rwanda had given the British government detailed assurances of fair treatment, its barristers told the Supreme Court on Tuesday that there was no evidence Rwanda had improved its treatment of asylum seekers.

It was known to the UN that Afghans had been turned around at Kigali airport and sent home weeks before the UK deal was struck.

The UN agency’s Laura Dubinsky KC said Syrians and Eritreans were also expelled without considering the risks.

Despite the deal with the UK, the key institutions and practices behind those decisions still existed.

Kigali’s ministers might have signed the migration partnership in good faith, but the security officials deciding the fate of refugees followed their own rules.

Even if genuine concerns existed, the country had extensive monitoring in place to address them. The country has every reputational and financial incentive to treat asylum seekers well.

With these arrangements in place, as well as the detailed commitments made to the UK under the £140m scheme, the plan could not be interfered with legally.