WASHINGTON, Nov 9 (Reuters) - United Arab Emirates bank Mashreqbank PSC (MASB.DU) has agreed to pay $100 million in penalties to resolve a U.S. government probe into violations of sanctions against doing business with Sudan, regulators said on Tuesday. Between January 2005 and February 2009, Mashreq sent $4 billion worth of Sudan-related payments through financial institutions in the United States, violating U.S. sanctions against Sudan, according to statements from the New York State Department of Financial Services (DFS) and the U.S. Treasury Department. From 2009 through 2014, the bank"s New York branch processed another $2.5 million in prohibited payments, DFS said. The investigation found the bank instructed its employees to avoid disclosing certain information sent between banks to conceal the violations and avoid triggering alerts or freezes on the transactions, DFS said. Mashreq said in an emailed statement the bank stopped the conduct "of its own volition" and had dedicated "significant resources" to boosting compliance policies and procedures.The Treasury Department"s Office of Foreign Assets Control said the bank had provided "substantial cooperation" throughout the course of the investigation. The Federal Reserve Board said in a separate statement it has issued a cease and desist order against the bank for having insufficient policies and procedures to ensure compliance with U.S. sanctions laws. The United States imposed the sanctions in 1997 after Sudan was designated a state sponsor of terrorism, prohibiting financial institutions from conducting business with the government and some designated individuals and companies. Mashreq also agreed to report on the status and sustainability of the bank"s compliance program.