US agriculture secretary Ann Veneman has resigned from the position after four years, during which she was responsible for handling issues such as BSE and food security.

President Bush paid tribute to Veneman, saying she had worked to promote economic opportunities for farmers and ranchers, ensure a safe and wholesome food supply, and sell American farm products around the world. There was no word on who might replace Veneman as agriculture secretary.

"I greatly appreciate Ann's leadership in ensuring that we responded quickly and effectively to protect the American food supply following the discovery of BSE in the United States and following September 11th… She has played a key role in opening markets and in ensuring a level playing field for America's farm products," said a statement from the president.