The sentence, the latest in Hanoi's crackdown on cyberspace dissent, triggered a protest by human rights group Amnesty International which expressed "profound shock" at the news.

Branded a spy, Nguyen Khac Toan was charged with espionage. Toan, a resident of the capital city, "received direct orders" from members of an exile "Vietnamese reactionary organization" based in France to gather letters of complaints and protests from those unhappy with Hanoi.

Amnesty said Toan had been a soldier and a mathematics teacher before going into business. "The branding of Nguyen Khac Toan as a 'spy' not only stifles freedom of expression through the use of loosely worded national security legislation but also criminalizes activities which are regarded as perfectly legal under international law and in most countries of the world," Amnesty said.

This incident bares striking resemblance to events of last month, where Hanoi jailed Le Chi Quang, who published criticisms of Vietnam's border pact with China on the Internet, for four years.