China has acknowledged for the first time that it is communicating with the United States about the case of Ling Wancheng, the brother of a one-time senior aide to then Chinese President Hu Jintao, in a case that could complicate ties.
Authorities have been tight-lipped about revealing any information about the man, Ling Wancheng, who is in the United States, sources have told Reuters.
China has demanded his return, the New York Times had earlier reported, in a case that could strain Sino-US ties if he were to seek to defect.
The government has given no details of any crime Ling is suspected of and he has not appeared on any wanted lists.
Last month, Liu Jianchao, who runs the ruling Communist Party's anti-graft watchdog's team trying to repatriate graft suspects, told reporters Ling Wancheng's case had nothing to do with him and he did not know who was in charge of it.
But on Friday (local time), in response to a question from Reuters at a news conference, Liu confirmed for the first time contacts with the United States about the case.
"As for the case of Ling Wancheng, the Chinese side is handling it and is communicating with the United States," Liu said.
Ling was in the United States, Liu told Reuters later.
On anti-corruption co-operation between China and the United States, Liu praised a "very positive" US attitude.
Last July, China said it would prosecute Ling Wancheng's brother, Ling Jihua, a one-time senior aide to Hu, after an investigation found that he took bribes and engaged in other corrupt behaviour.
Another brother, Ling Zhengce, has also been accused of corruption.
Ling Jihua's case has presented a dilemma for Beijing. His position is particularly sensitive because of his connection with Hu, President Xi Jinping's predecessor.
Since assuming power in late 2012, Xi has pursued a relentless campaign against corruption, warning that the problem could threaten the party's ability to retain power, though some analysts say he is also eliminating rivals.
China's efforts at repatriating corrupt officials overseas have long been hampered by Western countries' reluctance to sign extradition deals, partly out of concern about its judicial system.
Rights groups say Chinese authorities use torture and the death penalty is common in corruption cases.
Separately, Wu Yuliang, deputy secretary of the watchdog, the Central Commission for Discipline Inspection, said the governor of China's populous southwestern province of Sichuan, Wei Hong, was suspected of serious "discipline violations", a euphemism for corruption.