A former State Department official at the center of an espionage investigation is claiming reports of his involvement with a Taiwanese intelligence agent are inaccurate and distorted.

In a court filing Friday, lawyers for the veteran American diplomat, Donald Keyser, insisted that no harm to America’s security was done by his lengthy and sometimes intimate relationship with the agent, Isabelle Cheng.

“His communications were all in furtherance of U.S. government interests, even if he was answering questions that Ms. Cheng asked him,” Keyser’s counsel, Robert Litt and Mara Senn, wrote. “Even today, the government makes no allegation that any of the information Mr. Keyser disclosed was classified.”

Keyser, 63, pleaded guilty in December to charges that he lied about his relationship with Ms. Cheng, failed to disclose a trip he took to Taiwan in 2003, and kept thousands of classified documents at his home without permission. Last month, prosecutors asked to be released from the plea bargain, alleging that Keyser was not cooperating as promised and failed two lie detector tests.

The New York Sun reported Friday on an extraordinary 43-page court pleading in which prosecutors laid out in great detail Keyser’s alleged relationship with Ms. Cheng. The filing claims that Keyser, one of America’s top diplomats on Asian issues, relayed to the Taiwanese agent the contents of his conversations with President Jiang, in connection with a summit the Chinese leader attended with President Bush in Texas in 2002.

Over the weekend, Time magazine reported that Keyser’s wife, Margaret Lyons, is a senior Central Intelligence Agency official on loan to the Office of the Director of National Intelligence, John Negroponte. Court papers indicate that Ms. Lyons knew of at least some of the classified documents Keyser had at their Virginia home. Ms. Lyons also had brought some classified documents there, the magazine reported.

“I do not have the time, energy, stomach, or stamina to take on all the misstatements and mischaracterizations that have appeared, both in the government’s version or reality and in the press stories ‘inspired’ by this version,” Keyser wrote to friends on Saturday, in an e-mail obtained by the Sun. “The Time magazine version lacks only a nocturnal descent of alien spacecraft, a documented Elvis sighting, and a cameo performance by Michael Jackson to qualify for enshrinement in the National Enquirer hall of fame,” the ex-diplomat wrote, adding that the Time account contained “flagrant misrepresentations.”

Press representatives for the magazine could not be reached yesterday.

Keyser did not return a phone call and e-mail message seeking comment for this article.

In a brief interview yesterday, Mr. Litt declined to detail the purported errors in the press accounts. Asked whether Keyser was contending that the press reports mischaracterized the prosecution’s filing or that the articles passed on inaccurate information from the government, the defense lawyer said, “Obviously, it’s all coming from the government.”

In his filing Friday, Mr. Litt complained that part of the evidence supporting the prosecution’s effort to undo the plea bargain is being kept from Keyser. “For the government to ask the court to decide, based upon secret evidence, that the defendant has been untruthful, and therefore is not entitled to hold the government to its bargain, is reminiscent more of the Star Chamber than of courts of law in this country,” the attorney wrote.

Keyser has been free awaiting sentencing since he pleaded guilty last year. The judge in the case, Thomas Ellis III, has set a hearing next month on whether the government should be permitted to bring new charges against Keyser notwithstanding the plea deal.