(Adds details, paragraphs 5 and 6) WASHINGTON, Jan 17 (Reuters) - The World Bank said on Thursday its security staff was investigating a bomb threat made by telephone and told employees of its Washington headquarters to stay home on Friday. "The bank is working with law enforcement officials to determine the validity of the threat," the bank said in a statement. "As a precautionary measure, bank group management has decided to close all World Bank group leased and owned buildings in Washington on Friday," it added. The financial institution, which provides loans to poor countries to fight poverty, is located about a block from White House and employs about 8,000 in at least seven buildings in downtown Washington. The bank's sister organization, the International Monetary Fund, said it would be open on Friday but told employees they do not have to come in. In August 2004, security was beefed up around both institutions after U.S. intelligence warnings of possible threats to attack the New York Stock Exchange, the World Bank and IMF. (Reporting by Lesley Wroughton; editing by Jackie Frank)
