Over the course of the past month, U.S. Ambassador Nicholas Burns had the first meetings in more than five years with at least three U.S. citizens whom Washington says have been wrongfully detained, a senior U.S. official and family members said.

Burns met Li on March 16 in a Shanghai prison, Li's son Harrison said. Li, a computer scientist, has been held in China since 2016 and was handed a 10-year jail sentence in 2018 for espionage.

"The biggest message that my dad wanted to convey is to remind everyone in the U.S. government and the public that ... he's 100 percent innocent," Harrison Li said. "Of course the U.S. government knows this, but he said it just bears repeating."

Burns wanted to shake Li's hand but Chinese authorities did not allow that, Harrison Li said. The two could see and hear each other in an hour-long meeting through a floor-to-ceiling glass partition, he said.

Harrison Li said that when the ambassador asked his father what he hoped to do once he was released, he replied that he wanted to work on "improving relations between the United States and China."

China did not allow in-person visits during its prolonged COVID-19 lockdown.

Burns has also met with Mark Swidan, a Texas-based businessman who was convicted by a Chinese court in 2019 and David Lin, an American pastor detained in China since 2006, the senior U.S. official said, speaking on the condition of anonymity.

He did not provide the dates but said Burns visited the men "within the last few weeks" and that "this is the first time he's actually had a chance to get face-to-face."

Burns has accompanied consular officers on prison visits to U.S. citizens held in China, a State Department spokesperson said.

China's embassy in Washington did not immediately respond to a request for comment.

LIMITED U.S.-CHINA DIPLOMACY

Burns visited the three men at a time when relations between Washington and Beijing are the worst in decades following a series of disputes, including Washington accusing China of flying a spy balloon over the continental United States in February. A U.S. fighter jet shot it down.

China has said the balloon was a civilian research craft but the dramatic episode forced U.S. Secretary of State Antony Blinken to postpone a trip to Beijing.

Since then, there has been little positive diplomacy between the two countries aside from a brief and tense meeting between Blinken and top Chinese diplomat Wang Yi on Feb. 18 in Munich.

And last week Chinese President Xi Jinping visited Moscow where he and Russian President Vladimir Putin jointly denounced the United States.

The detainee issue often takes a back seat to more urgent issues in the U.S.-China relationship. Families of detained Americans say the freedom of their relatives should not be bundled up with challenging policy issues and are better addressed in a separate track focused on humanitarian matters.

(Reporting by Humeyra Pamuk; Additional reporting by Michael Martina; Editing by Don Durfee and Grant McCool)

By Humeyra Pamuk and Simon Lewis