By David Lawder

Washington (Reuters) – U.S. issues with China are “too serious” to be resolved with promises from Beijing to purchase more U.S. goods and any deal between the two countries must include a way to ensure commitments are met, U.S. Trade Representative Robert Lighthizer said in testimony at a Congressional hearing on Wednesday.

It is too early to predict the outcome of ongoing trade talks with Beijing, Lighthizer told the House of Representative’s Ways and Means Committee at a hearing on U.S.-China trade issues.

Lighthizer is the lead U.S. negotiator in trade negotiations with Beijing as the world’s two largest economies seek to find agreement to resolve a bitter dispute that has seen both sides impose tariffs on imports.

“The issues on the table are too serious to be resolved with promises of additional purchases. We need new rules,” Lighthizer said in prepared testimony.

Top U.S. and Chinese negotiators, including Lighthizer, met through the weekend in Washington, seeking to hammer out a deal to avert the increase in duties and ease a months-long tariff battle.

Citing progress in the discussions, U.S. President Donald Trump delayed a self-imposed March 1 deadline when the United States was scheduled to raise duties on $200 billion worth of Chinese goods from 10 percent to 25 percent. Trump said he may soon meet with China’s President Xi Jingping to finalize a deal.

China represents the “most severe challenge” ever faced by the American trade policymakers, Lighthizer said on Wednesday, noting Congressional support has been “critical in persuading China” to take the U.S. concerns more seriously.

(Reporting by David Lawder in Washington; Writing by Chris Prentice; Editing by Chizu Nomiyama and Susan Thomas)