BEIJING (Reuters) - China and the United States are in "advanced negotiations" on returning to China five of its most wanted corruption suspects who have fled to the United States, a state-run newspaper said on Wednesday.

China has vowed to pursue an overseas search dubbed Operation Fox Hunt for corrupt officials and business executives who have fled abroad, and their assets, part of President Xi Jinping's war on deep-seated corruption.

It has been pushing for extradition treaties but Western countries have been reluctant to help, not wanting to send people to a country where rights groups say mistreatment of suspects is a concern.

The English-language China Daily, citing a senior unidentified official at the ruling Communist Party's anti-graft watchdog, the Central Commission for Discipline Inspection, said China and the United States had speeded up talks on the return of the five.

"We will offer relevant evidence to our U.S. counterparts in a timely manner and leave for the U.S. at a proper time to conduct a joint investigation with our counterparts," the official said.

"We are in advanced negotiations with the U.S. to speed up the process for the fugitives' return."

The paper said the five included Yang Xiuzhu, a former deputy mayor of Wenzhou in the booming eastern province of Zhejiang, and Xu Chaofan, a former Bank of China regional director in the southern province of Guangdong.

The newspaper did not identify the three others, and made no mention of Ling Wancheng, the brother of a disgraced one-time aide to former President Hu Jintao, who is also in the United States.

China has said previously it is talking with the United States about Ling.

Media reported this year that U.S. officials had debriefed Ling who had provided nuclear secrets as well as personal information about Chinese leaders. His lawyer told Reuters in February that Ling denied handing over state secrets.

The unidentified official told the China Daily that China and the United States are in "advanced negotiations" to sign an agreement on "sharing confiscated assets".

The United States, Canada and Australia are among the places that graft suspects have fled to. Governments in those countries have insisted China goes through a proper legal process if it wants suspects back.

China has upset other countries by sending investigators to track corruption fugitives down without their knowledge.

"It is necessary to offer solid evidence to U.S. judicial officials and to make sure Chinese law enforcement officials are well-versed in U.S. and international law," justice ministry official Zhang Xiaoming told the China Daily.

(Reporting by Ben Blanchard; Editing by Robert Birsel)