The case involved four men -- an Iraqi, a Palestinian, a Syrian and a Somali -- who were forced to sleep on a mattress in the boarding area of Sheremetyevo Airport which was constantly lit, crowded and noisy.

They survived on emergency rations from the Russian office of the UN refugee agency.

The men spent from five to 22 months in these inhumane conditions awaiting a decision on their asylum applications, the European Court of Human Rights said in a statement.

"The confinement of the applicant asylum-seekers for lengthy periods in the airport transit zone without the possibility to enter Russian territory or a State other than that which they had left amounted to a de facto deprivation of liberty for which there was no legal basis in Russian law," the court's Grand Chamber ruled, confirming a 2017 decision by a lower chamber.

The court said in order to restrict people's liberty it must be "in accordance with the law" and in "humane conditions".

States must ensure such "minimum guarantees", it added, "despite the mounting 'migration crisis' in Europe".

Since 2015 European countries have seen an influx of refugees and migrants from the war-torn Middle East and poor African countries which has caused political tensions and anti-migrant sentiments.

The UNHCR ultimately was able to move the Iraqi and Syrian nationals to Denmark and Sweden while the Palestinian went to Egypt and the Somali returned to Mogadishu, saying he had given up hope.

The court ordered Russia to pay one of the applicants 15,000 euros ($ 16,609), two of them 20,000 euros each and the fourth one 26,000 euros.