Special Branch - the counter-espionage arm of the colonial police - was infiltrated by Kuomintang spies plotting terrorist attacks on the mainland and in Hong Kong, intelligence reports released by the British government reveal.
The reports also show that Beijing tipped off Britain about Kuomintang operatives working in the city - at a time when the nationalist party still had aspirations of reconquering the mainland from its base in Taiwan.
The series of intelligence reports from 1962-63 - sent by governor Robert Black to the Colonial Office in London - were among files released last week on the administration of Britain's former colonies.
A report from January 1963 described the 'arrest of an inspector and a constable on the staff of Special Branch who, in league together, were supplying ... information on current Special Branch activities'. Both policemen - who were not named - 'admitted working on behalf of the KIS [Kuomintang Intelligence Service] for some years'.
Another two Special Branch detectives went 'under interrogation' after aiding KIS agents in June 1962.
Eight KIS agents were arrested in July 1962 before they could carry out 'two sabotage attacks, one on the railway between Canton [Guangzhou] and Hankow [Hankou ] and the other on the Canton/Shanghai express train, which were planned to take place on the same day'.