WASHINGTON (Reuters) - Investment banker Howard Lutnick's exposure to China came into sharp relief on Wednesday, after Republican President-elect Donald Trump tapped him to lead the agencies that have become the tip of the spear in the U.S.-China trade war.

The financial services firms helmed by Lutnick have profited from ties to China, from BGC Group ( BGC ), which has a joint venture in Beijing with Chinese-state owned China Credit Trust, to Cantor Fitzgerald, which has helped take Chinese firms public in the United States.

The financial ties raise questions about whether Lutnick could be unduly influenced by Beijing when making decisions about whether to impose fresh tariffs and export curbs on China as United States Trade Representative and Commerce Secretary, lawmakers and ethics experts said.

"Mr. Lutnick's conflicts of interest in China appear to be substantial. How can the American people expect someone who is on the Chinese government's payroll to help level the playing field with China for working Americans?" asked Democratic Senator Ron Wyden, who chairs the Senate finance committee.

Cantor Fitzgerald, BGC group, and the Trump campaign did not immediately respond to requests for comment.

Democratic Senator Tim Kaine, who serves on the foreign relations and armed services committees, said he expects Lutnick "will be pressed about his financial connections to U.S. adversaries. It's crucial that our Commerce Secretary's top priority be the American people, not their personal business dealings."

Lutnick's financial services firm BGC Group ( BGC ) has a 33% stake, valued at nearly $28 million, in a joint venture with China Credit Trust, whose largest shareholder is state-owned China People's Insurance Company, according to the joint venture's website.

"In 2023, China Credit Trust will actively practise the mission and responsibility of a financial state-owned enterprise," the website says.

The joint venture, known as China Credit BGC Money Broking Company Limited, was licensed to operate in Beijing in 2010, as the first currency brokerage company there, according to the website, and provides brokerage and data services for domestic and foreign exchange markets as well as money, bond and derivatives markets.

The tie-up, according to a BGC press release, marked "the first Sino-foreign joint venture inter-dealer broking company to have been granted a business license by the China Banking Regulatory Commission to operate in Beijing."

'BUSINESS PARTNERS'

Lutnick is essentially "business partners" with the Chinese government, said Kathleen Clark, a professor of government ethics at Washington University in St. Louis. "This raises the specter of the Chinese government having leverage over the commerce secretary," she said. "Worst case scenario, it is surrendering control to a foreign government."

U.S. law bars any executive branch official from participating "personally and substantially" in a "particular matter" that would affect their financial interest.

According to Clark, Lutnick may not be seen as running afoul of that law, because any trade or export policy change he might impose would likely only have an indirect impact on his financial interest.

However, the emoluments clause of the constitution, she said, aims to keep foreign governments from having undue influence over U.S. policy via financial benefits for a U.S. official from a foreign source.

"That is why we have the foreign emoluments clause in the first place," she added.

Cantor Fitzgerald has also helped Chinese companies gain a foothold among U.S. investors. The firm underwrote Chinese biotech firm Adlai Nortye's ( ANL ) NASDAQ IPO last year, the first successful Chinese company to list since Beijing implemented new rules requiring Chinese firms to obtain a special filing before listing shares overseas.

Cantor Fitzgerald was the lead underwriter in two other deals in 2015 and 2019 that allowed Chinese companies GD Culture Group ( GDC ), a holding company for digital marketing and AI technology firm AI Catalysis Corp, and Aesthetic Medical International to trade on U.S. exchanges, according to the U.S. China economic and security review commission. Aesthetic Medical International was delisted by NASDAQ earlier this year.

The challenges faced by Lutnick in twinning his business and policy portfolios are highlighted by BGC's own September financial filing, which notes that U.S. China trade relations, which could be partially controlled by Lutnick, could impact company results.