The Bush administration put Thailand on notice yesterday that it will consider imposing retaliatory tariffs unless the country takes steps to improve the protection of American copyrights.

U.S. Trade Representative Carla Hills announced she is investigating Thailand's copyright enforcement practices.

"We have repeatedly expressed our strong concern to Thai officials at all levels that the rights of U.S. copyright holders are not adequately safeguarded," Hills said.

"Unfortunately, we have seen no improvement in Thailand's willingness to shut down the considerable illegal copying of U.S. movies, music, books and computer software or to ensure that U.S. companies obtain prompt and effective redress through Thailand's legal system," she said in a statement.

The investigation is being conducted under a provision of U.S. trade law known as Section 301. It allows the United States to boost tariffs on a country's goods if the administration finds that U.S. exports face unfair practices in another country.

Hills acted after receiving a petition Nov. 15 from the Motion Picture Association of America, the International Intellectual Property Alliance and the Recording Industry Association of America.

She said her office wants to consult with the Thai government immediately to resolve the problem.

If those talks fail, the administration would have the power to target a list of Thai exports to the United States for higher tariffs.