Jailed Hong Kong pro-democracy tycoon Jimmy Lai is not appealing his conviction under the city's controversial national security law.

His lawyers in Hong Kong have told news wires and local news outlets that they received "clear and definitive" instructions from Lai not to appeal, but did not give the reasons why.

Lai was convicted for conspiracy with others to publish seditious material and conspiracy to collude with foreign forces - charges which he has always denied - and was sentenced to 20 years in jail last month.

The tycoon faced a separate conviction for fraud, which was overturned last month in an successful legal appeal.

Lai's national security case had hinged on a meeting he had with the US' then vice-president Mike Pence and then secretary of state Mike Pompeo at the height of the 2019 pro-democracy protests.