The former leader of Hong Kong, Donald Tsang, has gone on trial for corruption.

Mr Tsang pleaded not guilty to three charges of bribery and misconduct, relating to a luxury flat in China.

He is the highest-ranking retired official to be tried for corruption in Hong Kong and faces possible jail time in a case that has worried a city known for its clean reputation.

Mr Tsang served as chief executive of Hong Kong from 2005 to 2012.

He faces charges of misconduct and accepting advantages as chief executive over events which took place near the end of his term, between 2010 and 2012.

Prosecutors say he rented the penthouse flat in China cheaply from a shareholder of broadcast company Wave Media.

In return, he allegedly approved their licence applications and chairmanship appointment without declaring a conflict of interest.

They also allege that the company paid for the flat to be redecorated for him, and Mr Tsang then nominated the interior designer who supervised the work for an honour.

Mr Tsang had previously insisted his conscience is clear.

The BBC's Helier Cheung in Hong Kong says Mr Tsang was initially a popular leader. He worked as a civil servant under British rule, and was awarded a knighthood for his services to Hong Kong.

He first came to power promising a "clean and efficient" civil service, according to the South China Morning Post.

But his term ended in scandal when the penthouse claims came to light, launching a three-year inquiry culminating in the trial.

His deputy was also jailed for bribery two years ago.