Hong Kong chief executive Carrie Lam has given her clear support to electoral reforms that would be likely to further exclude opposition voices and cement Chinese control over the semi-autonomous city.

Her comments came a day after a senior Beijing official signalled major changes to ensure Hong Kong is run by "patriots", a sign that China intends to no longer tolerate dissenting voices, 23 years after the former British colony was handed over to Chinese rule with a promise it could maintain its own rights and freedoms for 50 years.

Following China's imposition of a sweeping national security law on the city last year, authorities have moved to expel members of the city's Legislative Council deemed insufficiently loyal and rounded up veteran opposition leaders on charges including illegal assembly and colluding with foreign forces.

Government critics and Western governments accuse Beijing of going back on its word and effectively ending the "one country, two systems" framework for governing the Asian financial hub.

Ms Lam said political strife and unrest in the city, including anti-government protests in 2019 as well as demonstrations in 2014, showed some people are "rather hostile" to the central authorities in China.

"I can understand that the central authorities are very concerned, they do not want the situation to deteriorate further in such a way that 'one country, two systems' cannot be implemented," she said at a news briefing.

The Hong Kong government on Tuesday also said it plans to require district councillors - many of whom are directly elected by constituents and tend to be more politically independent - to pledge allegiance to Hong Kong as a special region of China. Currently, only the chief executive, high officials, executive council members, legislators and judges are required to take an oath of office.

Those who are found to take the oath improperly or who do not uphold the city's mini-constitution, the Basic Law, will be disqualified and barred from running for office for five years, according to the Secretary for Constitutional and Mainland Affairs, Erick Tsang.

Opposition figures swept district council elections following the 2019 protests and Beijing has since sought to prevent them from exerting influence on other aspects of the political system.

The move comes after an oath-taking controversy in 2016 ion which six pro-democracy legislators were expelled from the legislature after court rulings that they had not properly pledged allegiance because they mispronounced words, added words or read the oath slowly.

Hong Kong's legislature is expected to deliberate the draft legal amendments on March 17.