Incoming Chief Secretary Eric Chan on Sunday pledged to do his best to unite all sectors and assist the Chief Executive-elect John Lee to thoroughly implement One Country Two Systems principle.

Speaking at a news conference, Chan said he felt honoured to be appointed as Lee's deputy.

He noted the job came with great responsibility.

"I understand that with various difficulties that Hong Kong is facing, including livelihood issues and the coronavirus outbreak, residents have even higher expectations for the new government," he said.

He promised he would do his best to assist the chief executive, unite various sectors of society and coordinate government bureaus to implement policies that are in the interest of Hong Kong.

He added that he would ask government bureaus and departments to streamline procedures and improve efficiency to help residents solve problems quickly.

He added that authorities would closely liaise with their mainland counterparts to grasp the opportunities arising from the the development of Greater Bay Area.

The Secretary for Justice Paul Lam, meanwhile, said he had confidence in Hong Kong's rule of law, adding that he would strive to uphold it to ensure society is fair and just.

On safeguarding national security, he said it's Hong Kong's duty under the constitution and the Basic Law, as well as a prerequisite for the implementation of One Country Two Systems principle.

"We should use our common sense and think... if our national security is undermined and society becomes unstable, is it possible for us to have an environment that allows us to deal with other society problems?" he asked.

Speaking at the same news conference, Financial Secretary Paul Chan pledged to work with determination and innovative thinking to push for the development of Hong Kong's economy under the leadership of John Lee.