Missing mainland billionaire Xiao Jianhua received a diplomatic passport from Antigua and Barbuda just days before President Xi Jinping and Premier Li Keqiang met the prime minister of the tiny Caribbean nation in Beijing.
A copy of the passport – which was issued on August 8, 2014, and expired on the same date in 2016 – was passed to the South China Morning Post by a senior Antiguan diplomat, who said the 45-year-old tycoon was appointed as an "ambassador-at-large" for the country because of his extensive network.
The top-level meetings in the Great Hall of the People were followed by announcements of substantial investments in the country by China.
It was not clear if the diplomatic passport was renewed after it expired, but Xiao's appointment as ambassador-at-large for the country almost a year after being granted the document by Prime Minister Gaston Browne was extremely rare.
The only other recipient is Hollywood movie legend Robert De Niro, who along with Australian casino mogul James Packer, has pledged to invest US$250 million in the Caribbean island nation.
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In an interview with the Post, Sir Ronald Sanders, Antigua and Barbuda's Ambassador Extraordinary to the United States, said Xiao was granted special diplomatic status because of his "contacts with high level and high net-worth individuals who could benefit our nation's economy".
"Mr Xiao was granted the position for our country's benefit, not his benefit," Sanders said.
Xiao's whereabouts remain unknown after he disappeared in mysterious circumstances from his residence in the five-star Four Seasons Hotel in Central last month, sparking renewed concerns over possible unauthorised mainland law enforcement activity in Hong Kong.
Official confirmation that Xiao held a diplomatic passport – and the reasons it was issued – will fuel speculation the billionaire businessman's ties to senior mainland figures and their business dealings could be one of the reasons behind his disappearance.
Antigua and Barbuda has since tightened its rules for issuing diplomatic passports and sought to reassure the public over the integrity of the country's recently introduced Citizenship by Investment Programme, applications for which have been dominated by high net-worth individuals from the mainland.
However, Sanders said: "Mr Xiao and Mr De Niro were not granted either their passports or their special status under the Citizenship by Investment Programme.
"Mr Xiao's passport expired after two years in August 2016. I am not able to comment on whether or not it was renewed."
Browne's Beijing meeting with Li Keqiang in August 2014 lasted for an hour and led to an agreement to expand cooperation in clean energy, agriculture, tourism, education and health care.
Li said China would also help with the construction of highways, airports and ports and provide financial aid, goods and no-interest loans to the country, which was struggling under the weight of a US$1 billion debt – almost equivalent to its annual gross domestic product – in the wake of the 2008 financial crisis.
The Antigua Defence Force was also given HK$25.3 million by China to bolster the integrity of its borders.
Meanwhile, Hong Kong's security chief, Lai Tung-kwok, said on Wednesday that until now there was no indication that Xiao had left the city against his will or that mainland public security officers had enforced law in the city.