Thien stayed in the north. His initial enthusiasm for the country's new-found independence soon turned to terror. The communists turned North Vietnam into a prison. Poets and writers were terrorised into silence. More than 170,000 peasants were killed in the Maoist-styled ''land reform'' campaign.

Thien, who had graduated from the Hanoi Faculty of Letters, was asked by a teacher friend in 1960 to substitute for him in a history class. He was horrified to find that the textbook claimed it was the Soviet Union that had defeated the Japanese army and ended World War II. He told the class it was the United States that defeated Japan in 1945 after dropping two atomic bombs on Hiroshima and Nagasaki.

This landed him in prison for 3½ years. Stripped of pen and paper, he composed his poems in his head and committed them to memory, sometimes by reciting them to his jail mates.

In 1966, he was jailed again, this time for more than 11 years after his ''reactionary'' poems were circulated in Hanoi and Hai Phong. He lamented the communist victory over South Vietnam in 1975:

We are now united in one block of suffering
We are now united in one block of hatred
O South Vietnam the day of your loss
I suffer from one thousand, ten thousand agonies.

Thien was released in 1977 but was under constant police surveillance. In 1979, fearing that he might not live if imprisoned for a third time, he determined to try to have his poems taken out of Vietnam.

He ran into the British Embassy in Hanoi, shouting ''I'm not crazy! I'm not crazy!'' at the startled staff. The lanky and dishevelled man pulled out from under his shirt a thick roll of paper - his hand-written collection of 400 poems - and asked British diplomats to ferry it out to the free world. For this, he spent 12 years in prison, mostly at the infamous Hanoi Hilton, where senator John McCain was once held.

His poetry first appeared in the US in the early 1980s under the title A Cry from the Abyss, then published as Flowers of Hell when it was translated into English French, German, Dutch, Spanish, Chinese, Czech and Korean.

Thanks to the international following this generated, Thien won the Rotterdam International Poetry Award in 1985. In 1988, he also won the Freedom to Write award.

Amnesty International adopted him as a prisoner of conscience in 1990. Thien was finally released in 1991 and resettled in the US in 1995, the same year he was honoured by Human Rights Watch. In exile, he published two short-story collections, Hỏa Lò (Hanoi Hilton) and Hai Truyện Tù (Two Prison Stories), and continued to speak out against communist oppression in his homeland.

His jailers had told him they would rather keep him alive and see him suffer. He described his survival and his eventual release to freedom as a miracle.

Thien dreamed:
A day will come when we can throw away
The guns, the shackles, the Communist Party
            and their bloody flag
A day will come when we can reverse our tragic fate
And wake up from our nightmare.

Among Thien's jail mates was a prominent human rights advocate, Father Nguyen Van Ly, a Catholic priest. Father Ly's bravery and grace in the face of adversity touched Thien deeply. Before he died, Thien asked to be baptised as a Catholic.