US Secretary of State Hillary Rodham Clinton Monday called the death of US envoy Richard Holbrook a "sad day" for the United States, dpa reported.
"Tonight America has lost one of its fiercest champions and most dedicated public servants," Clinton said in a statement.
"Holbrooke served the country he loved for nearly half a century, representing the United States in far-flung war-zones and high-level peace talks, always with distinctive brilliance and unmatched determination," she said.
The diplomat made numerous trips to Afghanistan and Pakistan during the two years he has been the State Department's special envoy. A former ambassador to Germany, Holbrooke also helped broker the 1995 Dayton Peace Accords, which ended the Bosnian civil war.