LONDON (AP) — Two men accused of helping Hong Kong authorities gather intelligence in the U.K. pleaded not guilty Thursday to violating Britain's National Security Act.

Chung Biu Yuen, 64, and Chi Leung Peter Wai, 39, are accused of agreeing to undertake information gathering, surveillance and acts of deception likely to assist a foreign intelligence service.

Yuen was the office manager of the Hong Kong Economic and Trade Office in London and Wai had worked as a U.K. Border Force officer.

They had previously pleaded not guilty to a charge of foreign interference for allegedly breaking into a home in the U.K. Wai had also denied a count of misconduct in a public office for allegedly searching Home Office databases without justification when working as a border officer.

The two, who are free on bail, face a March 10 trial in London’s Central Criminal Court.

Officials in Hong Kong, a former British colony that returned to Chinese control in 1997, have voiced concerns over the charges. Beijing officials strongly criticized the case.

A case against a third suspect, Matthew Trickett, an immigration enforcement officer, was discontinued after he was found dead in a park in May. A prosecutor said Trickett attempted suicide after he was charged. Authorities said his death was not considered suspicious.