HONG KONG (Reuters) - A top Hong Kong government official has urged Britain to let the public "know the truth" about the unexplained death of a man charged this month with aiding the territory's foreign intelligence service.

Algernon Yau, Hong Kong's Secretary for Commerce and Economic Development, met with Britain's deputy counsel-general to discuss the incident and express concern about the death in Maidenhead, southern England, according to a statement from the Commerce and Economic Development Bureau, released late on Thursday.

British police are investigating the unexplained death of 37-year-old Matthew Trickett, one of three men charged with two offences under Britain's National Security Act. The law was passed last year and introduced new measures to target threats from foreign states.

Trickett, a 37 year old former Royal Marine with a private security firm, had been granted bail at a May 13 court hearing along with Chung Biu Yuen, 63, an office manager at the Hong Kong Economic and Trade Office in London, and Chi Leung Wai, also known as Peter Wai, 38.

The trio are accused of assisting a foreign intelligence service between December and May by "agreeing to undertake information gathering, surveillance and acts of deception" in Britain, according to the charges.

Hong Kong was under British rule for 156 years before reverting to Chinese sovereignty in 1997.

Yau said Britain should fairly handle the matter and give an open account of the incident, "especially the death of a person who was arrested by the UK Police and reportedly a UK immigration officer."

He added that it was important to "let the public know the truth and prevent unwarranted speculation" and ensure the normal operation of Hong Kong's Economic and Trade Office in London.

The Chinese Embassy in London accused Britain of fabricating the charges against the men and said it had no right to interfere in Hong Kong's affairs.

(Reporting by Farah Master; Editing by Lincoln Feast.)