The former leader of Hong Kong's Donald Tsang has been sentenced to 20 months in jail following a corruption trial.

Tsang, 72, was Hong Kong's chief executive between 2005 and 2012 and is its most senior official to be convicted.

He was found guilty of misconduct for not revealing a conflict of interest after he did not disclose plans to lease a luxury flat from a major investor in a broadcaster, which later got a government licence.

He approved three applications from Wave Media between 2010 and 2012 at a time when he was in talks with the property mogul and Wave stakeholder Bill Wong Cho-bau, over a luxury penthouse.

In mitigation, his defence lawyer Clare Montgomery QC had asked for a suspended sentence and that the "ordeal" of the trial had taken a toll on Tsang's health.

He received more than 40 letters of support from allies and opponents.

"Mr Tsang must now serve the rest of his life out with the knowledge that his reputation has been ruined and his legacy shattered," she said during Monday's mitigation hearing, the South China Morning Post reported.

The Judge Andrew Chan had said he would sentence him to 30 months in jail but reduced it by 10 months because of his contribution to Hong Kong and his good character, the Associated Press reported.

The jury failed to reach a verdict on another bribery charge for which he will face a retrial later in the year.

Donald Tsang
Former Hong Kong Chief Executive Donald Tsang, pictured in January 2017 arriving at Hong Kong's High Court, has been jailed for 20 months for corruptionReuters