SANTA ANA, Calif. — U.S. Rep. Neil Abercrombie, D-Hawai'i, and two other House Democrats have written a letter to Secretary of State Condoleezza Rice asking for her help in gaining the release of two political activists arrested in Vietnam. One of those arrested is a Honolulu resident.

Abercrombie and California's Rep. Loretta Sanchez Grove and Rep. Zoe Lofgren wrote on behalf of the U.S. citizens who were arrested Saturday while holding a meeting in Ho Chi Minh City.

"We are disappointed to hear that the government of Vietnam has arrested United States citizens in Vietnam for reportedly having a peaceful discussion," the letter read.

"Not only do we ask you to work to return these United States citizens to the United States, but we ask you to convey to the government of Vietnam that the arbitrary detention of United States citizens is unacceptable."

Vietnamese security police detained six pro-democracy activists, including the two U.S. citizens, a French citizen and a Thai citizen, over the weekend, according to the U.S.-based pro-democracy group Viet Tan.

The two U.S. citizens are Nguyen Quoc Quan, a co-founder of the Vietnamese Professional Society and mathematician who lives in Sacramento, and Truong Van Ba, a community activist who lives in Honolulu.

U.S. Embassy officials confirmed that a U.S. citizen was arrested over the weekend but released no further details. They are requesting an interview with him and investigating the reasons for his arrest.

According to a Viet Tan statement Truong Van Ba was born in 1953 and emigrated to the United States in 1979. He has operated a food catering truck and has two children living in the United States and two grown children in Vietnam.

Press freedom advocacy group Reporters Without Borders condemned the arrest of the activists and Frenchwoman Nguyen Thi Thanh Van, whom the group called a freedom-of-expression activist.

"We call for their immediate release since they were only engaged in peacefully promoting freedom of expression," according to a statement released by the group.

Advertiser reporter Sean Hao contributed to this report.