South Korea said Thursday that it would send its top trade negotiator to the United States to try to revise an agreement on American beef imports that has set off weeks of demonstrations against the government of President Lee Myung-bak.

Trade Minister Kim Jong-hoon, who negotiated a free trade pact with the United States last year, is to go to Washington on Friday to seek modifications in the terms of a deal to resume imports of American beef, signed in April.