PALO ALTO, Calif. — Evidence is mounting that at least some of the 11 men indicted in California last year for allegedly planning the overthrow of the government of Laos may have believed their plan had the tacit approval or even the outright support of the CIA.

Documents filed in federal court in Sacramento last week show that in 2004 a retired CIA employee held detailed discussions about a military intervention in Laos with one of the key defendants in the case, General Vang Pao, an aging Hmong leader who fought an American-backed secret war against the Laotian government in the 1960s and 1970s.

According to an FBI report, the former CIA operative, Michael Spak, told prosecutors and defense attorneys in the case last summer that he talked with the general for three to four hours about military tactics and provided him with written cost estimates and “talking points” for a military campaign.

Mr. Spak, who faces no charges, said the general wanted to work with the Lao government to ease the suffering of the Hmong people. The ex-CIA man said he told the general that some military pressure on Vientiane was essential.

“In response to Vang Pao’s ideas, Spak told him that political pressure alone had no chance of working,” the FBI report said. “Spak recommended a two-pronged approach to pressure the Lao government including both a political and military track. He described the military track as consisting of direct and indirect sabotage and small-scale military engagements.”

The former CIA officer also “recommended” buying explosives in Thailand or through his own security firm, Virtual Defense and Development International Inc., the FBI memo said.

Mr. Spak told the lawyers that he advised the general that the firm would get involved only if the American government approved. “Spak offered to discuss the military approach with his contacts in the CIA, and Vang Pao agreed,” according to the FBI report on Mr. Spak’s interview.

Mr. Spak said that soon after the February 2004 meeting he reached out to a CIA contact who routed the inquiry to an officer on the agency’s Southeast Asia desk. “Good luck” was the message Mr. Spak said he got back from the contact. In a point that could be important to the general’s defense, the former CIA operative said he never advised the general about the dismissive reply from Langley.

Mr. Spak told The New York Sun that some aspects of the FBI report were not accurate, but he declined to elaborate and said he did not have time to discuss the matter further last night.

Defense lawyers allege that the undercover Alcohol, Tobacco, and Firearms agent who conducted the sting operation stoked the defendants’ perceptions that the CIA and other government agencies would take part in the coup attempt. “I’m willing to bet … that the CIA is aware of what’s going on there,” the agent told an Army veteran who allegedly played a key role in the plot, Harrison Jack, according to a transcript of a secretly taped March 2007 conversation. “They’re going to know when to come in.” The agent also talked about flying prisoners of war back to America on a C-5 military transport and speculated about which air force base would be best suited to receive it.

“Travis or Beale. Beale would probably be better,” the ATF agent told Mr. Jack, according to the transcripts.

Another Hmong defendant, Lo Cha Thao, boasted of meeting with high-level CIA officials and told Mr. Jack in phone calls that the agency was ready to jump in. “The CIA gave us a mission to go and find the exact heartbeat of the country. … We got the top guy, like the CIA guy, giving under the table strategies,” Lo Cha Thao said, according to surveillance transcripts. “They are waiting on us and they mobilized everything over there already. They’re just waiting for our call.”

Prosecutors did not respond to a request for comment yesterday, but one told a judge at a hearing last year that the talk about the CIA’s participation was fantasy.

“There was no CIA involvement or any other federal government involvement in this case other than the investigation by ATF and the FBI,” a prosecutor, Robert Twiss, said. “This is a complete fabrication by the defendants carried forward from Lo Cha Thao to Harrison Jack.”

Mr. Twiss also told the court that the agent’s talk about the CIA was idle speculation. “The snippets you saw don’t suggest any CIA activity. What it suggests is two guys who are Defense Department veterans talking about things Defense Department veterans talk about. … Virtually everyone in this room has speculated as to national defense policy, what the CIA will do here or there, what the Army will do. This is a completely usual, not unusual, discussion,” he said.

Defense lawyers did not return calls seeking comment for this article, but a lawyer for Lo Cha Thao has said publicly that the meeting with the top CIA officials never occurred. In a joint court filing last week seeking more information on any CIA contacts and on American policy toward Laos, defense attorneys said their clients might not be guilty if they thought their plan had official approval. “To the degree a defendant believed that such consent existed, he had no intent to engage in a criminal conspiracy,” the lawyers wrote. Arguments of entrapment and “defense of others” are also possible, the filing said.

However, prosecutors said some defendants were warned that it was illegal to plot such a coup from America.

A former federal prosecutor, Laurie Levenson, said the 78-year-old former general might prevail at the trial, which is not expected until next year. “Even if you thought the government was in the right, there’s a sympathy factor from the jury,” she said, adding that jurors were sure to ask, “At one point he was a friend. Why are you going after him now?”

Mr. Spak’s dealings with the general have not been previously reported. However, portions of the ATF surveillance transcripts appeared in the New York Times in May.