David Truong, the Vietnamese expatriate charged with passing classified State Department documents to Hanoi officials in Paris, testified yesterday that he had collected information on U.S. Vietnamese relations for more than 10 years and often turned it over to American officials as well as to friends in Vietnam.

Indeed, Truong testified in the ninth days of his espionage trial, he often amassed information from libraries, newspapers, letters and other sources and gave it to U.S. senators, foreign policy experts and university professors here. He also sent the same type of information to Vietnamese publications abroad, to his family in Vietnam, and to the Vietnamese delegation to the United Nations, he said.

At first the purpose of the effort was to help end the war, Truong testified, and when the war was over, the purpose of the information was to help rebuild his war-torn country.

Moving chronologically through the details of his life in the ninth day of his espionage trial in Alexandria, Truong said:

"I strongly feel in my position I should help to rebuild Vietnam . . . and bring Americans and Vietnamese together. After 30 years of war and a lot of things that happened to divide families . . . and all of the suffering each of us has gone through it's time to turn a new page and do something more meaningful than fighting."

The government has charged that Truong, along with form United States Information Agency employe Ronald L. Humphrey, funneled classified State Department documents through an espionage network to Hanoi officials in Paris. Humphrey is accused of stealing the documents from the United States Information Agency and giving them to Truong, who gave them to a courier with instructions to deliver them to Vietnamese officials in Paris, according to the indictment.

Humphrey and Truong gave the documents to the Communists the government contends to give the Vietnamese an edge in Paris in negotiations occurring between the United States and Vietnam.

Humphrey testified Monday that he gave confidential classified State Department documents to Truong, a Capitol Hill lobbyist, out of his desperate love for his Vietnamese common-law wife, Kim, and her five children who were trapped by the Communists in Vietnam.

Humphrey said on the stand that he had hoped the information would help improve relations between Vietnam and the U.S. and in some indirect way help secure the release of Kim and her children.

For several days during the unprecedented trial, government attorneys have presented evidence to try to show that classified diplomatic cables, airgrams and other documents involved were properly classified, injured the United States and aided the vietnamese. Truong is expected to testify specifically about the cables when the trial resumes on Monday.

Truong testified yesterday that some of the evidence that the government presented to the jury in an effort to prove that Truong was involved with the Communists was part of his studies or relaxation reading.

Truong said he collected information, advised government officials on Vietnam affairs and lectured extensively as an anti-Vietnam war activist in the 1960s. His activities increased after his father, an unsuccessful peace candidate for the presidency of Vietnam in 1967, was imprisoned after that defeat, he said.

Truong said his father spent 5 years in prison at hard labor at the instruction of President Nguyen Van Thieu, who was supported by the United States. Truong said yesterday he doesn't hate the United States for what happened to his father.

One of the documents marked "secret" that the government took from Truong's apartment during a search on Jan. 31, when he was arrested, was presented as evidence against Truong last week. Truong said yesterday, however, that the document "basically describes his (Truong's father's) political background and political support he had from Vietnamese groups. Apparently they typed on top of it 'secret'. It was supposed to be secret for his country."

Courtroom spectators, many of whom support Truong, chuckled.

While he was lecturing across the country Truong said he was unable to get a work permit from the Immigration and Naturalization Service. He said he would borrow money from his sister in Los Angeles when he was broke.

"Were you paid by the Vietnamese government?" asked Truong's attorney, Marvin L. Miller, "No," Truong replied, laughing.

Truong testified that over the years he has set up Vietnamese organizations in this country to help inform Vietnamese born people living in America and abroad about the situation in Southeast Asia. The organizations published a newsletter, Truong said.

The newsletter of the Vietnamese Resource Center, a group he help set up in Cambridge, Mass., was printed in English and Vietnamese. "Something like four-fifth of the U.S. Senate and two-thirds of the House of Representatives read that," Truong testified. "I think there were people in the State Department who read that too."

The newsletter was distributed to "40 or 50 countries," Truong said, and the Association of Vietnamese in Paris, a group of Vietnamese in France who met and discussed politics.

The officers of the association, Huynh Trung Dong and Nguyen Ngoc Giao, are named as unindicted co-conspiritors in the alleged espionage plot that is the subject of the current trials. Truong said Giao "at that time was the person who was on the editorial committee of the newsletter." Dong is "also on the editorial committee of the newsletter," Truong said.

Rather than pay each other for newsletter subscriptions Truong said his group and the group in Paris would exchange newsletters without charge.

A double agent for the FBI and CIA testified last week that she delivered packages between Truong and Giao and Dong, but she testified she didn't know what was in them.

Truong said he has continued to send information to the Vietnamese in Paris, for their newsletter.

Truong also testified that he gave information to the Vietnamese delegation to the U.N. The head of that delegation, Ambassador Din Ba Thi, was named as an unindicated co-conspiritor in the alleged espionage ring. Thi never asked Truong to spy for him and never paid him for his informtion, Truong testified. "I sent them press source items that dealt with Vietnam, Southeast Asia, congressional documents and reports, he said. Truong sent them the materials because Vietnamese U.N. officials are not allowed to leave New York, he said.

"Was that different information from what you used for your research?" Miller asked. "No it was the same thing. I just had to pick up a few more copies."

"Was the information classified?" Miller asked. "It could have been in 1949," Truong replied.

"In early 1977 Ambassador Thi asked me to get a congressional document on a hearing dealing with those missing in action . . . that took place before a subcommittee of the house," Truong said.

Another document Thi requested was "a statement made on the floor of the Senate by Sen. Hubert Humphrey that dealt with the necessity of the U.S. lifting the embargo on Vietnam," Truong testified.

"Did the ambassador ever ask you to spy on te United States?" Miller asked. "No, sir," Truong answered emphatically.

"Did you get friends in the United States so you could spy?" Miller asked, "No, sir," was Truong's reply.

Truong testified that Thi never asked him for anything else, but Truong continued to send the delegation press items, technical books and reports of congressional hearings.

Thi denied charges that he was involved in any espionage scheme. Several days after he was named in the indictment, however, the State Department requested that Thi leave the country. Thi refused but Hanoi recalled the ambassador several days later. At that time the U.N. mission called the charges a "blatant fabrication."