Dang Xuong Hung, who served as the consul from 2008 to 2012, when he formally withdrew from the Vietnamese Communist Party, told Geneva station Leman Bleu yesterday that he had applied for Swiss asylum last October.
"The Berlin wall fell 25 years ago, but Vietnam is still under a communist regime," he said.
"The Vietnamese Communist Party persists with its aim to continue the dictatorship, to continue with a one-party regime."
"There is an economic crisis, a political crisis, and crisis in education, in health," he said, adding that he hoped his defection would prompt others to follow his lead.
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The news came ahead of a review before the UN's top human rights body of Vietnam's rights record.
In a letter to the Vietnamese delegation attending the so-called Universal Periodic Review before the UN Human rights Council, Dang voiced empathy with diplomats who "care about Vietnam, but are shackled by invisible bonds".
"Once we dare speak the truth, we won't have to waste time dishonestly concealing the facts," he wrote.
Rights groups meanwhile decried that an independent journalist and civil society advocate scheduled to speak on the sidelines of the UPR in Geneva this week had been blocked from leaving Vietnam.
"We are alarmed at the Hanoi government's attempts to silence Pham Chi Dung," Hillel Neuer, head of Geneva-based rights group UN Watch, said in a statement.
UN Watch and Vietnamese pro-democracy group Viet Tan had invited Pham, who publicly quit the Communist Party last December, to speak at a side event tomorrow focused on Vietnam's responsibilities as a new member of the Human Rights Council.