Carrie Lam on Saturday said she had no regrets about pushing ahead with the extradition bill in 2019, a move that sparked massive protests and led to the arrest of thousands of people.

Speaking on an RTHK programme which looked back at her five-year term, the outgoing Chief Executive reiterated that the extradition bill had been needed to prevent Hong Kong becoming a "safe haven" for fugitives.

She said she had apologised at the time because the government had done a poor job in explaining such a complicated legal matter to the public in layman's terms, while the other side had, what she called, an "overwhelming" amount of propaganda.

"I do not think the government made a mistake in introducing this bill," Lam said.

The Chief Executive said she had tried to mend the rift in society after she took office, and that Beijing had taken an inclusive approach towards opposition lawmakers.

But she said the extradition bill saga demonstrated that "harmony at a superficial level" was meaningless and what happened was unavoidable.

"Whenever we faced something that could be used to challenge the country and touch its bottom line, the opposition forces would come out, and come out stronger every time," Lam said, citing the example of the protests in 2003 against the Basic Law Article 23 security legislation, Occupy Central in 2014, and the Mong Kok riot in 2016.

Asked what she planned to do after she retired, Lam said she didn't have any particular work in mind. She also said she would not set up a think-tank - like one of her predecessors did - as this would be like intervening with, or influencing the work of, the administration.