NAIROBI, KENYA, JAN. 24 -- Somalia's government has embarked upon a diplomatic damage control mission in the United States and Britain aimed at dispelling growing criticism by western governments of its human rights record. The mission, which will include a visit to Washington by the Somali prime minister, comes in the face of Somalia's deepening economic and political crisis, exacerbated by reports that the government of Gen. Mohammed Siad Barre is stockpiling chemical weapons in warehouses near its capital, Mogadishu. The Somali government has denied possession of chemical weapons. This week it also accused the United Nations of dooming 400,000 Ethiopian refugees in northern Somalia to likely starvation after the world body announced it would phase out food shipments to 10-year-old refugee camps there. The U.N. decision followed reports from its envoys that Somalia has distributed guns at the camps and is using the refugees to help fight its civil war. The Somali government said it has armed the refugees for self-defense. The claims and counterclaims are difficult to assess, as the government has kept virtually all foreign journalists out of Somalia since serious fighting between its Army and the rebel Somali National Movement began in May. At least 50,000 civilians have died in the fighting and large numbers of civilians have been detained, according to a report by the London-based human rights group Amnesty International. Another 400,000 Somalis are believed to have crossed into Ethiopia to avoid the fighting, according to the U.N. High Commissioner for Refugees. A private Australian relief agency working in northern Somalia last month closed down its operations, citing gross abuses of human rights. The agency, Community Aid Abroad, said the Somali strategy in the north amounts to a "scorched earth" policy against northern civilians. The U.S. Congress, moved by such charges as well as Amnesty International's description of a pattern of systematic torture of political opponents of Siad's government, has moved to block more than $55 million in past and current U.S. economic aid to Somalia, pending human rights reforms and an effort by the government to find a political solution to its civil war. Last month, Britain also suspended $9 million in foreign aid, citing concern about human rights. British Foreign Secretary Geoffrey Howe, speaking in Djibouti two weeks ago, said the British government was "deeply concerned" about authoritative reports that chemical weapons had been received in Somalia. Those reports, which come from witnesses, say canisters of the nerve gases Soman and Sarin were unloaded from a Libyan Airlines civilian flight to Mogadishu on Oct. 7, according to Richard Greenfield, a British citizen and senior adviser for nine years to the Somali government before his dismissal last year. Greenfield has been criticized by the Siad government as a supporter of the northern rebels. {In Washington, a State Department official said the United States is aware of the reports but could not confirm them, staff writer David B. Ottaway reported. The Somali government had categorically denied any intention to obtain or use chemical weapons in its struggle with rebel forces in the north, he said. The United States has made clear to the Somali government its strong opposition to the use of such weapons "anywhere in the world," the official added. {A Pentagon official said several months ago that there may have been confusion over a shipment of napalm canisters Somalia had received, possibly from Libya, that was at first thought to be chemical weapons.} Somalia, a U.S. ally that received $5 million in military assistance last year, is a nation of 5.7 million people divided into several clans. For most of his long rule, Siad governed by building coalitions among competing clans while maintaining absolute power. In recent years, Siad's political control has weakened and the coalitions have frayed. Last May, the Somali National Movement, whose members are drawn mostly from the northern Issak clan, captured several northern towns. The government's counteroffensive included the shooting of civilians in the streets and during house-to-house searches, according to Amnesty International. The government initially refused to admit that civilian deaths had occurred and has strictly controlled access to the region since then. The rebels have demanded economic and political reforms, and say they will not negotiate with the government until Siad has been removed from office. Somalia badly needs the suspended U.S. and British payments to fulfill debt obligations to the International Monetary Fund. Default on its IMF debt could cut off lending from a number of foreign countries. In response, the government has begun a public relations campaign. On Monday, Somalia's prime minister, Lt. Gen. Ali Samatar, met with Howe in London to deny that Somalia has chemical weapons and to argue for the release of the $9 million. Samatar is expected to arrive in Washington on Friday. In London, Samatar reportedly told Howe that his government had released a number of political prisoners and was attempting to make peace with the northern rebels. According to Greenfield and a western diplomatic source, however, that consists largely of trying to mollify northern business interests rather than negotiating with rebel leaders. A western diplomatic source in Mogadishu said this week that the Siad government, under economic pressure, has made some progress in human rights. He said the government had released political prisoners and had responded to a request by Amnesty International to visit the country. No date for that visit has been set. A U.N. inspection team that visited the north late last year reported that Ethiopian refugees were carrying weapons supplied by the Somali Army. The U.N. team reported that, with the Army's encouragement, the refugees carried out extensive looting in several northern towns. The rebels claim that more than 40,000 Ethiopians have been armed by Somalia, but other sources put the figure at a few thousand.