An informant for the FBI and the CIA testified yesterday in the second day of an espionage trial in U.S. court in Alexandria that she carried documents given to her by Vietnamese expatriate David Truong to Vietnamese officials in Paris.

The informant, Dung Krall, testified yesterday that she met Truong in Hecht's parking lot at the Landmark Shopping Center in Alexandria last June 22, and received a grocery bag of documents from him. She later gave the package to the FBI.

When the FBI returned the package to her, she delivered it to Vietnamese officials in Paris on Aug. 24, she testified, and one of the officials gave her a letter to give Truong in return.

About Sept. 12, Krall gave Truong the letter at a Washington restaurant.

Krall's description of how she delivered documents from Truong to Hanoi officials is a central element in the government's efforts to prove that Truong engaged in espionage by passing secrets to Communist Vietnamese.

The government contends that Truong's co-defendants Ronald L. Humphrey, stole documents from the United States Information Agency where he worked and gave them to Truong. Truong, in turn is charged with giving the stolen papers to Krall to deliver to Hanoi officials.

Krall's testimony took up most of the second day of the espionage trial in Alexandria, as she explained details of her work as a courier as attorneys for Truong attacked her credibility as a witness.

Truong's attorneys suggested that Krall, a paid informant, was untruthful and demanded money and benefits from the U.S. before she would cooperate in their investigation.

Krall, 32 testified that although the CIA and FBI paid her for her services as a counter-intelligence agent she did not demand money or benefits before she would work for them. "I love my work and I believe in it," Krall said.

One of Truong's attorneys, Michael E. Tigar, asked Krall if she had asked the government to help her father defect from Vietnam where he is the Communist Vietnamese ambassador to the Soviet Union. Krall replied, "No," and said her father said he wanted to stay in Vietnam.

Krall acknowledged that the government paid her $2,153 so that she and her husband could move from London, where her husband, a naval intelligence officer, was stationed for a short time, to the United States. She testified that the CIA paid her an additional $1,000 at the time of the trip. She also received per diem and travel and living expenses while on assignment, Krall testified.

Krall also testified, under Tigar's cross-examination, that the U.S. government spent $11,800 to relocate members of her family from Vietnam, where she said they would be endangered if she testified in the Truong case. She also testified that she was paid $1,200 a year by the government and will continue to receive it through the end of this year.

Krall emphatically denied that she had ever requested that she be paid a $45,000 bonus as a termination payment when she ended her work with the CIA. She said after repeated questioning by Tigar that the government paid $250 a month rent for an apartment for her sister who already lived in the United States.

At one point yesterday, Tigar read a letter from her CIA supervisor Robert Hall, who Tigar said wrote in a memorandum that Krall suggested she would not complete an assignment if she didn't get a raise. Krall denied she made the statement.

In other questioning, Tigar suggested that Krall was untruthful in dealing with the Vietnamese. "You didn't tell Mr. Nam (a Vietnamese official) you were on a olandestine mission for the CIA?" Tigar asked.

"You think I'm crazy?" Krall replied, smiling.

"Then you were untruthful," Tigar said.

"He never asked me if I worked for the CIA," Krall testified.

Krall said that she pretended to be in the import-export business when she met with Vietnamese officials in Paris. "That was my cover to get to Paris."

"You mean you would tell untruths to hurt your enemies?" Tigar asked. "Yes," Krall replied.