HANOI (REUTERS) - Vietnamese human rights lawyer Nguyen Van Dai has been freed from prison and flown to Germany, activists and a diplomat said on Friday (June 8), two months after he was convicted of attempting to overthrow the state and given a 15-year jail sentence.

Mr Dai, founder of the group "Brotherhood for Democracy", was released from prison late on Thursday along with another group member, Ms Le Thu Ha, who was serving a nine-year prison sentence, the US-based human rights group Viet Tan said.

Vietnam's Foreign Ministry and the German Embassy in Hanoi did not immediately comment.

Mr Dai's release was confirmed by a European Union official in Vietnam.

"On plane to Germany," the official, who declined to be identified, said in a text message when asked about Mr Dai's whereabouts.

Viet Tan said in statement that Mr Dai's wife, Ms Vu Minh Khanh, and Ms Ha were also on the flight to Frankfurt.

Mr Dai and Ms Ha were among six Brotherhood members charged with activities "aimed at overthrowing the people's administration" and convicted by a Hanoi court in April.

The Brotherhood conducted anti-government activities to "build multi-party democracy", according to a copy of the official indictment.

Mr Dai and Ms Ha did not appeal the verdict, but four other members of the group had their appeals rejected on Monday, with the court upholding their prison sentences of between seven and 12 years.

Despite sweeping economic reform and increasing openness to social change, Vietnam's ruling Communist Party retains tight media censorship and does not tolerate criticism.

"Vietnam must end its systematic repression against human rights defenders who simply seek to reform the government in the country where they live," Phil Robertson, deputy Asia director of New York-based Human Rights Watch, said on Sunday.