The US ambassador to Vietnam met the leader of an outlawed Buddhist church who is under de facto house arrest, the US embassy said.
Ambassador Raymond Burghardt met Thich Huyen Quang "during an hour for a private conversation" in Quy Nhon, in the central province of Binh Dinh, embassy spokesman Tom Carmichael said.
Quang, 86, is the patriarch of the Unified Buddhist Church of Vietnam.
He and his deputy, Thich Quang Do, 75, were arrested with other monks after an October meeting and accused of being in possession of state secrets and trying to reorganize the church with the help of outside forces.
They have since remained under de facto house arrest.
The church's overseas information arm Tuesday said two senior church dignitaries had written to President Tran Duc Luong and Prime Minister Phan Van Khai asking them to release the monks.
Foreign ministry spokesman Le Dung Wednesday said he had received no information about the letter.
"Thich Huyen Quang and Thich Quang Do were not arrested... So far, the two are living and practising their religion as normal," he added.
The church was formally banned in 1981 because it refused to come under the ruling Communist Party's control.
Hanoi regularly repeats that religious freedom is guaranteed by its constitution and rejects allegations by the Paris-based International Buddhist Information Bureau as "ill-willed sheer fabrication."
In its annual report in December on international religious freedom, the US State Department grouped Vietnam in a worst offenders' category of totalitarian and authoritarian states which view religious groups as "enemies of the state".