The Chinese government on Tuesday approved sweeping changes to Hong Kong elections that would ensure only "patriots," or those loyal to Beijing, can govern the territory in a significant rollback of democracy.

The National People's Congress Standing Committee, the core decision-making body of China's parliament, unanimously approved amending methods of electing Hong Kong's leader and legislators.

The overhaul mainly involves expanding the power and membership of the Election Committee tasked with picking Hong Kong's chief executive.

Committee membership will be expanded from 1,200 members to 1,500 members with newcomers from grassroots and Chinese townsmen associations, according to the just-approved amendment.

Among the others to be added are members of district crime-fighting and fire safety committees, local delegates of China's political advisory body and Hong Kong members of national organizations.

While new members are added to the committee, the 117 seats reserved for locally elected district council members are being discarded.

Those occupying the seats have been the most openly elected on the committee, and most of the current members hail from the pro-democracy camp.

The chief executive will need at least 188 nominations from across different committee sectors to qualify for standing in the once-every-five-year election.

The 70-member Legislative Council will be increased to 90 seats, with directly elected seats cut from the current 35 to 20, while trade-based seats to be cut from 35 to 30. The Election Committee will select the newly added 40 seats.

Candidates in all elections will be vetted by a newly formed qualification review committee whose members will comprise a handful of senior Hong Kong officials.

Some candidates may need to go through national security screenings. The Committee for Safeguarding National Security, established last year under a sweeping national security law, will make findings as to whether they are qualified.

Decisions made against individuals over national security concerns cannot be challenged in court.

Chief Executive Carrie Lam said the Hong Kong government strongly supports the amendment and will carry out corresponding local legislation as soon as possible.

"The amendments improve the electoral system of the HKSAR (Hong Kong Special Administrative Region), thereby establishing a political structure that upholds the 'one country, two systems' principle, reflects the actual situation of Hong Kong and ensures 'patriots administering Hong Kong,'" Lam said in a statement.

Lam also defended the move to discard the seats reserved for district council members on the Election Committee, saying that the district councils are "advisory bodies" for the government on district matters.

The exclusion of the district councils was therefore "to restore them back to their intended constitutional role, Lam said.

And reducing the number of directly elected seats in the Legislative Council is needed to keep from power people who may sabotage Hong Kong and endanger national security, she said.

The next leadership election is scheduled for March 2022, with a new chief executive taking office in July that year.

The next Legislative Council election, postponed for a year from last September purportedly over pandemic concerns, is expected to be held in December, not in September, according to Lam.

The Standing Committee adopted the amendment to annexes to Hong Kong's Basic Law, the former British colony's mini-constitution, in a 167-0 vote.

Lam said related legislation is expected to be introduced to the territory's legislature next month and enacted by the end of May.