BEIJING - China's yet-to-be-announced new ambassador to the United States Qin Gang headed to Washington on Tuesday, according to people familiar with the matter, amid worsening relations between the world's two largest economies.

Qin left a day after rare high-level talks in the northern Chinese city of Tianjin between U.S. Deputy Secretary of State Wendy Sherman and senior Chinese diplomats ended with both sides reiterating existing positions and no specific outcomes reached.

Relations between Beijing and Washington deteriorated sharply under former U.S. President Donald Trump, and the Biden administration has maintained pressure on China in a stance that enjoys bipartisan support but threatens to deepen mistrust.

Qin, 55, is replacing Cui Tiankai, who at 68 has passed the retirement age for senior Chinese ambassadors, the sources familiar with the matter said. When Cui ended his eight years at Washington last month, he was China's longest serving ambassador to the United States, and is a seasoned and well-respected figure in both Beijing and Washington.

Qin who is China's vice foreign minister and whose recent past portfolios have included European affairs and protocol, has no prior U.S.-related experience, according to his biography on the foreign ministry website.

"It will take some time for Qin build up his network of contacts in the political, security and diplomacy circles in the United States," said Li Mingjiang, an associate professor of international relations at Singapore's S. Rajaratnam School of International Studies.

Qin has done two stints as foreign ministry spokesman between 2006 and 2014, and stood out among his peers for being one of the earliest Chinese diplomats to make sharp comments in defence of China.

"Qin is likely to appear tougher than Cui when engaging with the Americans," Li said.

"But given how China-U.S. ties are now largely constrained by structural factors, such as domestic pressure and strategic competition, there is a limit to how much an ambassador can actually do to influence ties."

(Reporting by Yew Lun Tian; Editing by Raju Gopalakrishnan) ((LunTian.Yew@thomsonreuters.com;))