Britain to Evacuate Its Citizens From South Sudan LONDON - In a sign of mounting international concern about fighting in South Sudan, Britain said Thursday that it would evacuate British nationals as clashes were reported to have spread following claims of an attempted coup. The Foreign Office said that around 150 of the estimated 500 Britons in the newly created country had been in touch with British officials, many of them wanting to leave the country. The developments came a day after the South Sudanese Army said that it had lost control of a town in the north of the country. South Sudan declared its independence in July 2011, after years of struggle to break away from the Arab-dominated north of Sudan. But in the past few days, President Salva Kiir has accused his former vice president, Riek Machar, of attempting to overthrow him - a charge Mr. Machar denied Wednesday. Tension has been simmering since Mr. Kiir dismissed his cabinet, including Mr. Machar, in July. The British Foreign Office said it had sent a plane on Thursday to airlift its citizens from Juba, the capital of South Sudan. Diplomats, quoted by Reuters, have said that up to 500 people have been killed in the days since Mr. Kiir appeared in camouflage uniform at a televised news conference on Monday to say his government had thwarted an attempt to overthrow it. The United Nations Mission in South Sudan reported on its Twitter feed on Thursday that civilians were seeking shelter at its facilities in six of South Sudan's 10 states. The fighting has raised fears that the fledgling nation is headed toward civil war, adding to Africa's woes at a time when France has sent troops to a former colony, the Central African Republic, to try to quell an escalation of sectarian strife. The United Nations has said that violence is spreading in remote areas of South Sudan, including the northern town of Bor, the capital of Jonglei state about 125 miles north of Juba, where ethnic tensions between followers of Mr. Kiir and Mr. Machar had erupted into fighting at two Army barracks, according to Reuters. Gérard Araud, the French ambassador to the United Nations and the current president of the Security Council, told the BBC in an interview that the fighting "has the potential for civil war" between the country's two principal ethnic groups, the Dinka and the Nuer. Mr. Araud said that the United Nations had 7,000 to 8,000 troops in South Sudan but that they would not intervene in the fighting because their mission was to protect civilians. On Wednesday, Mr. Kiir was reported to have said that he was ready for talks. A group of East African foreign ministers was scheduled to travel to South Sudan on Thursday to try to mediate in the conflict. In a report on Wednesday, the International Crisis Group, a research group based in Brussels, said, "The scenario many feared but dared not contemplate looks frighteningly possible: South Sudan, the world's newest state, is now arguably on the cusp of a civil war." "What has for some time been a political crisis within the ruling Sudan People's Liberation Movement has now spilled over into an army that has long been riven by internal problems, including ethnic divisions and tensions," it added. The blurred lines between these institutions, senior political figures and ethnic communities - as well as wide-scale arms proliferation - make the current situation particularly volatile.