Hong Kong leadership hopeful Carrie Lam testified in a high-profile corruption trial Thursday where she described the accused -- a former city leader -- as her "role model".

Donald Tsang is charged with misconduct and bribery while he was Hong Kong's chief executive and is the highest-ranking official to be taken to court for graft.

The trial comes at a time when residents are losing faith in Hong Kong's elites, as a string of corruption cases fuel public suspicions over cosy links between authorities and business leaders.

Lam was made secretary for development in 2007 during Tsang's administration and said he "had been my role model in my career as a public servant", when she was called as a prosecution witness at the city's High Court.

Lam answered "yes" when the defence counsel asked whether Tsang did his "honest best to serve the public".

Tsang, 72, was leader from 2005 to 2012 and has pleaded not guilty to three charges of misconduct and bribery, each with a maximum jail sentence of seven years.

He is accused of failing to disclose his plans to lease a luxury penthouse in the neighbouring city of Shenzhen from a major investor in a broadcaster -- which at the time was seeking a licence from the Hong Kong government.

Tsang allegedly approved the company's application for the licence, and also failed to declare that an architect he proposed for a government award had been employed as an interior designer for the flat.

Lam denied knowledge of the Shenzhen property.

She also said she had not come under pressure when she nominated the architect for the award after he was suggested to her department by the chief executive's office.

"Of course I made my own judgement," she said.

The prosecution has called Tsang's behaviour a betrayal of public trust.

In 2012 Tsang apologised for separate allegations that he accepted inappropriate gifts from business friends in the form of trips on luxury yachts and private jets.

Lam was most recently tough deputy to unpopular current chief executive Leung Chun-ying.

She stepped down earlier this month to run for election in March and is widely seen as Beijing's favourite candidate to lead the semi-autonomous city.

But since announcing her bid Lam has been accused of being out of touch with ordinary people.

She was this week ridiculed for revealing she did not know where to buy toilet paper late at night and appearing hesitant using a subway turnstile.