With his bouffant black hair, white short-sleeve shirt and endless boring speeches, he certainly seemed like a high-ranking Communist party official.

But Zhao Xiyong, who has claimed since 2010 to be the head of China 's State Council Research Office - giving him the rank of vice-minister - was an artful impostor.

For years, Mr Zhao pulled off a pitch-perfect impersonation of a leader from Beijing that local officials in the south western province of Yunnan, being subordinate in rank, did not dare to question.

He was allowed to give keynote talks at important conferences, seated with pride of place at the banquet table, and grovelled to by local officials.

He would also frequently tour the province, delivering vague and empty speeches and greeting local Communist party chiefs.

A local radio station dutifully reported one of his visits, to a vegetable farm to the city of Yuxi, where he met the county's agriculture officials and led a delegation of 89 people on a tour of drought-affected areas.

"The government should make full use of its economic advantage, actively learning from other's experiences, and explore a new path that incorporates scientific research, production and marketing," he said, without any obvious meaning, to polite applause.

A chubby and jovial figure who often dangled a cigarette, Mr Zhao was an adept politician. In one speech, he praised the Yunnei car engine company as a well-loved brand in Europe and claimed it would "open a UK manufacturing base in January 2013".

He only seems to have overreached himself last November, when he promised delegates at a conference in Kunming, the capital of Yunnan, that the government had approved a new free-trade zone to boost the city's economy.

"Kunming, as the core city in the plan, will receive a huge boost to its industry and economy," he said. "I sincerely hope the local government and party creates a good environment for companies that invest here."

Perhaps to his dismay, his surprise announcement made the headlines in the local newspapers and prompted a flood of queries to the State Council for confirmation.

On March 8, the State Council, China's cabinet, responded unambiguously.

"We have recently received reports that Zhao Xiyong is pretending to be the head of the State Council Research Office and an official of vice-minister level. We announce that he does not work for the State Council, and that no research team has ever been sent to Yunnan province," said a statement.

Mr Zhao's current whereabouts, and indeed his true identity, are unknown.

If caught, he could face three to ten years in prison.

"He performed his official duties without a secretary, he organised events, made speeches, handled social activities, wrote calligraphy and cut ribbons, he successful cheated the State Council and provincial officials. He is in no way different from a real official!" commented one wag on the Chinese internet.

Additional reporting by Valentina Luo