Flags of the U.S. and China are placed ahead of a meeting between U.S. Secretary of Agriculture Sonny Perdue and China's Agriculture Minister Han Changfu at the Ministry of Agriculture in Beijing on June 30, 2017.

The Trump administration on Tuesday said that China has failed to alter its "unfair" practices at the heart of the U.S.-China trade conflict, adding to tensions ahead of a high-stakes meeting later this month between U.S. President Donald Trump and Chinese President Xi Jinping.

The findings were issued in an update of the U.S. Trade Representative's "Section 301" investigation into China's intellectual property and technology transfer policies, which sparked U.S. tariffs on $50 billion worth of Chinese goods that later ballooned to $250 billion.

"We completed this update as part of this Administration's strengthened monitoring and enforcement effort," USTR Robert Lighthizer said in a statement. "This update shows that China has not fundamentally altered its unfair, unreasonable, and market-distorting practices that were the subject of the March 2018 report on our Section 301 investigation."