Nairobi - Eritrea has defended its controversial policy of decades-long national service from which at least 5 000 people flee each month, saying it has "no other choice" due to threats from long-standing enemy Ethiopia.Dismissing a United Nations commission of inquiry on the human rights situation in Eritrea - which said the government is responsible for systematic and widespread human rights abuses on an almost unprecedented scale - Asmara justified the mass, open-ended conscription of its people.Eritreans make up the second-largest number of people risking the dangerous crossing of the Mediterranean Sea, after Syrians, running the gauntlet of ruthless people smugglers and dangerous waters in the hope of reaching the European Union.But Asmara said UN criticism of the national service - which begins for children in their last year of high school - "is effectively denying the Eritrean people the right to defend themselves in an existential crisis against a foe 15 to 20 times their total population size," said a foreign ministry statement posted at the weekend.The UN report described horrific torture, including electric shock, near drowning and sexual abuse. Its nearly 500-page report released in early June details how the country, under Isaias Afwerki's iron-fisted regime for the past 22 years, has created a repressive system in which people are routinely arrested at whim, detained, tortured, killed or go missing.Final and extra-ordinary conclusionsAsmara said the report was filled with "bias, errors, unsubstantiated and illogical claims, misrepresentations and evidentiary weaknesses that are used to reach final and extraordinary conclusions".Eritrea, which broke away from Ethiopia in 1991 after a brutal 30-year independence struggle, remains in a tense stand off with Addis Ababa after a 1998-2000 border war. Troops still eyeball each other along the frontier, with Ethiopian soldiers defying an international ruling to leave Eritrean land."By law national service is only required for 18 months," Eritrea's Ministry of Foreign Affairs said."However, due to Ethiopia's refusal to abide by a final and binding ruling, and the international community's continued indifference to this deliberate flaunting of international law by Ethiopia, the government of Eritrea had been left with no other choice but to rely on its population to defend its independence and sovereignty."Eritrea, which denied investigators entry to the country, also criticised the evidence as "emanating from self-described "human rights activists" with an "openly declared regime-change agenda".It also rejected accusations its leadership could be guilty of possible war crimes."There is no evidentiary support for the claim," Asmara said.