WASHINGTON — A former C.I.A. officer suspected of helping China unravel the agency’s spy network in that country was indicted on Tuesday on a charge of conspiring to commit espionage.

The officer, Jerry Chun Shing Lee, 53, was arrested by F.B.I. agents in January after federal prosecutors accused him of illegally possessing classified information. But the new charge reflected a willingness of prosecutors to disclose sensitive details they might have been reluctant to acknowledge publicly.

According to prosecutors, two Chinese intelligence officers approached Mr. Lee in April 2010 and offered to pay him for information. The intelligence officers “provided Lee with a series of email addresses so that he could communicate covertly with them,” court papers said, and he received instructions from Chinese intelligence officers until at least 2011.