WASHINGTON, Jan 5 (Reuters) - The United States on Wednesday imposed fresh sanctions on Bosnian Serb leader Milorad Dodik, who aims to take the Serb Republic out of Bosnia's armed forces, and designated an entity linked to him, according to the U.S. Treasury Department's website.

Bosnia is experiencing its gravest political crisis since the end of the war in the 1990s, reviving fears of a break-up after Bosnian Serbs blocked the work of the central government and Serb lawmakers voted to start pulling the autonomous Serb Republic out of state institutions. (Reporting by Daphne Psaledakis and David Ljunggren)