The official, Donald W. Keyser, was arrested on Wednesday and appeared in federal court in Arlington, Va., The New York Times reported.
Keyser's attorney, Robert Litt, was unavailable for comment Thursday, and a phone call to Keyser's home was not immediately returned. At the court appearance Wednesday, Keyser was released on a $500,000 bond and a preliminary hearing was set for Oct. 13.
The State Department declined comment on the case Thursday because it involves an ongoing investigation.
A criminal complaint charges that Keyser made "a materially false, fictitious, and fraudulent statement and representation." Keyser is not charged with espionage and the government has made no formal allegation that he mishandled secrets.
In an affidavit accompanying the criminal complaint, an FBI agent alleges that Keyser met with a Taiwanese intelligence agent during a three-day trip to Taiwan last September and then failed to disclose the trip for a background check.
Keyser joined the State Department in 1972 and has held a number of posts dealing with Asian policy, including postings to embassies in Tokyo and Beijing. Earlier this year, he was promoted to the post of principal deputy assistant secretary for East Asian and Pacific affairs. He resigned on July 30.
The affidavit by special agent David R. Farrell states that Keyser "had extensive involvement in, and responsibility for, the foreign policy of the United States with respect to East Asia and the Pacific."
In his posts, Keyser had Top Secret security clearance and regularly saw classified information, the affidavit states.
According to the affidavit, Keyser went on an official trip to China and Japan in late August and early September 2003. During his visit, he took a three-day side trip to Taiwan.
The United States walks a diplomatic tightrope on Taiwan, the island where Chinese nationalists fled after the communist takeover on the mainland in 1949.
Because China claims Taiwan as a renegade province, the U.S. does not recognize Taiwan as a country. But a 1979 law obligates the government to help defend the island against any invasion, and the U.S. sells military equipment to Taiwan.
According to the affidavit, because the U.S. has no formal diplomatic relations with Taiwan, Keyser was not allowed to go there on official business.
In an interview with the FBI, Keyser claimed the visit was for sightseeing. But Keyser admits that during his visit he met a Taiwanese intelligence officer.
Keyser is supposed to report all foreign travel and contacts with foreign officials. But he did not, the FBI alleges, and admits he did not even tell his family. He claimed three days of leave in Tokyo when he was actually in Taiwan, the affidavit reads.
Keyser did not list the trip this year when filling out a routine background investigation form this year that "requires employees to disclose information about their foreign travel and contacts with foreign governments."
The affidavit lists a set of meetings between Keyser and the Taiwanese officer, known as "foreign person one." The FBI says it saw Keyser and the Taiwanese officer together in May boarding an Amtrak train bound for New York City and watched them drive in July to a parking lot in Maryland.
On a Saturday later in July, the FBI saw Keyser meet the officer and the officer's boss, known as "foreign person two" at the Potowmack Landing Restaurant in Alexandria.
"During this meeting, FBI agents observed Keyser hand two letter-sized envelopes (one each) to Foreign Person One and Foreign Person Two that appeared to bear U.S. Government printing," the affidavit reads. It cites other meetings where documents were shared.
On Sept. 4, at a meeting at the Alexandria restaurant, FBI agents saw Keyser pass a document labeled "discussion topics" to the two Taiwanese agents. The FBI stopped the Taiwanese agents as they left and recovered the six-page document from them.
"Analysts at the Department of State who have reviewed that document have advised the FBI that portions of the document were derived from material to which Keyser had access as a result of his employment with the Department of State," the affidavit said.
Keyser told the FBI that the Taiwanese officer had requested the meetings and that he typed talking points for each session.
The Times reports that during the Clinton administration, Keyser was one of six State Department employees disciplined for a security breach involving a missing laptop computer. He was reassigned.
In another case involving official documents, federal investigators are trying to determine whether a mid-level Pentagon officialon Iran to the American Israel Public Affairs Committee, the major Israeli lobbying group in Washington, and whether AIPAC in turn passed it to Israel.