Vietnam has released a dissident writer and pro-democracy activist and deported her to the United States on humanitarian grounds, officials said Friday.

Tran Khai Thanh Thuy was released from prison Wednesday and put on a flight to the United States, an official with the Ministry of Public Security said on condition of anonymity, citing policy.

Thuy has been reunited with her daughter and arrived safely in San Francisco, said Rep. Loretta Sanchez, who has been advocating for the dissident's release since she was detained in 2009.

The U.S. State Department had pressed for Thuy's release, and U.S. Embassy spokesman Beau Miller praised Vietnam for freeing her.

"Cooperation on human rights remains an important facet of our bilateral relationship," he said. "We continue to urge the government of Vietnam to respect internationally recognized human rights."

Miller said Thuy's daughter also will be admitted to the U.S.

Thuy, 50, was among a small circle of dissidents in Vietnam who have promoted a multiparty system, which is not tolerated by the Communist government.

She was convicted last year of assaulting two people in a traffic dispute outside their Hanoi home. An appeals court upheld her 3 1/2-year prison sentence, but international human rights groups allege that undercover police recruited thugs to attack Thuy, then charged her with assault to punish her for her political activity.

The Vietnamese government released a statement Friday saying Thuy was being resettled in the U.S. on humanitarian grounds.

Sanchez, who represents a Congressional district with a large Vietnamese community, said, "The unfair arrest and conviction of Tran Khai Thanh Thuy for peaceful dissent and democratic demonstration never should have taken place."

Thuy has been active in the dissident community since 2006, when she started organizations to help workers and assist farmers whose land had been confiscated by the government. Thuy, who worked for many years in Vietnam's state-controlled media, later wrote for an online pro-democracy newspaper and published a blog.

The New York-based Human Rights Watch last year honored Thuy and five other Vietnamese writers its annual Hellman/Hammet award for their courage in the face of political persecution.