Amnesty International has detected a worrying new trend of oppression and a clamp down of free speech in Communist-run Vietnam after two songwriters, Tran Vu Anh Binh and Vo Minh Tri, were both convicted by a court in Ho Chi Minh City and sentenced to six and four years in prison, respectively, for writing songs, which criticised government policy.

The two men were detained in late 2011 on charges of spreading anti-government propaganda, and their arrest comes just weeks after three bloggers were also accused of spreading anti-government propaganda and jailed for between four and 12 years.

On hearing of the latest government clamp down, Amnesty International released a statement, calling for the songwriters' release. They said: "This is a ludicrous way to treat people just for writing songs,'' adding that "These men are prisoners of conscience, detained solely for the peaceful exercise of their right to freedom of expression through their songs and non-violent activities, and should be freed."

The government, with its state-run media, doesn't allow freedom of expression. So bloggers and performers, who operate in free media to criticise or highlight corruption and human rights cases, involving Communist Party leaders, are a target for the Vietnamese Prime Minister.

Written and presented by Ann Salter.