US Senate Majority Leader Chuck Schumer accused Chinese firms of "fuelling" a drug addiction crisis in the United States, as he met with officials in Shanghai on the first leg of a visit to the country.
Schumer is the latest high-level American official to visit China as Washington seeks to ease tensions with Beijing.
He met Saturday with Chen Jining, the ruling Chinese Communist Party's chief official in Shanghai, according to a pool report, stressing the United States "does not want to decouple our economies".
He also raised the issue of Chinese firms' role in the fentanyl drug addiction crisis in the United States.
"This is not the government but this is Chinese companies," he stressed.
"They are fuelling the fentanyl crisis that is poisoning communities across the United States," he said.
Washington this week sanctioned a China-based network for producing and distributing chemicals used to make drugs -- including those fueling the deadly fentanyl crisis in America.
Beijing has said it opposes the sanctions, and insisted the opioid problem is "rooted in" the United States and not its responsibility.
Schumer also said Sunday he would seek to raise Beijing's alleged unfair trade practices during his visit.
"Many of our constituents feel that in instances China does not treat American companies fairly when we talk to our American companies, they bring this up including many of them that are here," he told Chen.
"We believe we need reciprocity, allowing American companies to compete as freely in China as Chinese companies are able to compete here," he said.
- 'Very productive' -
Bloomberg has reported his delegation is seeking a meeting with President Xi Jinping.
The delegation's plane landed early afternoon in Shanghai, China's economic powerhouse, where they were greeted by US Ambassador Nicholas Burns.
Asked about his expectations for the visit, Schumer said he was hoping for "very productive discussions".
Accompanying Schumer is Republican Senator Mike Crapo, who represents the state of Idaho -- home to chip giant Micron, currently in the crossfire of US-China disputes over semiconductors.
Four other senators are joining the delegation.
China has said it welcomes the delegation and that it hopes it enhances the lawmakers' "understanding" of the country.
Beijing's foreign ministry said the trip would "promote dialogue and exchanges between the legislative bodies of the two countries, and inject positive elements into the development of China-US relations".
US media reported the group will seek to raise issues ranging from the climate for US businesses in China to human rights.
The delegation will also stop off in South Korea and Japan, The New York Times reported, citing the senators' offices.
It is the latest in a series of visits by US officials to China, as both sides aim to defuse rankles across a range of security and economic issues that have been at their highest levels in years.
Secretary of State Antony Blinken, Treasury Secretary Janet Yellen and Commerce Secretary Gina Raimondo, as well as Climate Envoy John Kerry, have all visited China this year.
And President Joe Biden on Friday said he may meet Xi in San Francisco in November as Washington and Beijing push to reset ties, but added that nothing is scheduled yet.
"There has been no such meeting set up, but it is a possibility," Biden told journalists after reports that they were set to meet during the Asia-Pacific Economic Cooperation (APEC) summit in San Francisco.
Biden is set to host leaders from across the region on November 16 and 17 in the California city, and speculation has mounted that it could be the venue for a rapprochement.
The White House had begun making plans for a meeting on the sidelines of the summit in a bid to stabilise relations, The Washington Post reported, quoting one official as saying "it's pretty firm".
Chinese Foreign Minister Wang Yi is expected to visit Washington ahead of the APEC summit.