WASHINGTON - The United States and China made "incremental progress" on a number of issues in the recent high-level bilateral talks, US trade chief Michael Froman said on Tuesday.

In a conversation with Tom Donohue, president and CEO of the US Chamber of Commerce in Washington, US Trade Representative (USTR) Froman said he saw encouraging signs for US-China relations as Chinese President Xi Jinping met with US President Barack Obama in California in June and the two sides concluded the annual Strategic and Economic Dialogue (S&ED) in Washington earlier this month.

For example, during the recent round of S&ED, "China agreeing to start negotiations on a bilateral investment treaty based on the principles of national treatment and pre-establishment, and based on the 'negative list,' is a potentially very important development and could help drive reform in China," said Froman, who took up the post of USTR last month.

"We took that as an encouraging sign and look forward to engaging with them" on a lot of issues, he added.

Froman also said that China's new leadership was grappling with a set of economic issues, including economic transition, air pollution and food safety, and hoped these moves would have positive effects on bilateral relationships.

In terms of the Trans-Pacific Partnership (TPP) trade negotiations, which involved 12 countries and completed 18th round of talks, Froman said he was "cautiously optimistic" that a final agreement could be reached by the end of this year.

"It's an incredibly complex negotiation ... it' s a challenge for everybody but I feel good, we've got momentum and there's a real focus on getting it done," he said.

Turning to the transatlantic trade deal between the United States and the Europe Union, which concluded the first round of talks earlier this month, Froman noted that the key of the agreement was not only eliminating tariffs and addressing non-traditional trade barriers, it's also eliminating unnecessary differences on regulatory standards between the two sides. That's "going to be tough," he said.