Three African men have taken their challenge against Hong Kong's system for vetting refugee claims to the highest court, arguing that the government must assess the applications itself rather than passing the responsibility to the UNHCR. Lawyers for the men, who have not been identified by name, made their case at the Court of Final Appeal yesterday, after previous rulings against them by the lower courts. Hong Kong is not a signatory to the United Nations Convention Relating to the Status of Refugees, and is therefore not subject to obligations under it. The government has an arrangement with the United Nations High Commissioner for Refugees whereby the latter handles claims for refugee status. The men are arguing that Hong Kong has an obligation to make the assessments itself. They say non-refoulement - the principle that a state must not send a person back to a place where they may be persecuted - is a fundamental principle of customary international law from which no state can deviate, and that it is part of Hong Kong law. The government has a duty to "make an informed and fair decision", said the men's lawyer, Michael Fordham QC, and must conduct enquiries into refugee claims to assess them. The appeal, which began yesterday, is scheduled to last three days. The director of immigration and secretary for security are respondents. The case began as an application for judicial review, which was dismissed. An appeal was also unsuccessful. The three men were given leave to go to the top court last December. The men - one in his 20s and the other two in their 30s - remain in Hong Kong. All three earlier had their applications for refugee status rejected by the UNHCR, as well as their appeals. One of the men is from the Democratic Republic of Congo, and the other two are from the Republic of Congo. The man from the Democratic Republic of Congo is an ethnic Tutsi who says he had been trained as an army intelligence officer. He claims he could not leave his unit, which had committed human rights abuses, without endangering his life and his family. He said he was arrested in 1998 and tortured, before fleeing to Rwanda, then Uganda, Korea and finally Hong Kong in 2004. One of the claimants from the Republic of Congo says he and his family had been the victims of ethnic unrest, and had to flee after being pursued by an armed gang. He arrived in Hong Kong in 2004 via Ethiopia and Thailand. The third appellant claims he was forced to flee after distributing literature for, and joining, opposition politics in his country. He arrived in Hong Kong in 2003. The hearing continues before the Court of Final Appeal, comprising Mr Justices Patrick Chan Siu-oi, Roberto Ribeiro, Robert Tang Ching, Kemal Bokhary and Anthony Mason.