A newly established eligibility committee will ensure that extreme anti-China candidates are not allowed to contest the Hong Kong Election Committee polls, which start on Sunday, experts said.

The subsector elections for the Election Committee will be the first since the 13th National People's Congress, China's top legislature, amended Annex I and Annex II of the Basic Law in March in a bid to ensure that "patriots administer Hong Kong". The two annexes concern the methods for the selection of the Hong Kong Special Administrative Region's chief executive and the formation of the Legislative Council.

The reform enlarged the Election Committee to 1,500 members representing five sectors and extended its power from simply choosing the city's chief executive to also nominating Legislative Council members. It also asked Hong Kong to establish the Candidate Eligibility Review Committee to assess and validate the eligibility of candidates for the Election Committee, chief executive and Legislative Council elections.

The Hong Kong government announced in early August that it had received 1,056 nominations for the 980 seats open to contest this year, compared with 1,539 nominations in the last vote in 2016.

Some media reports have pointed out that the drop in the number meant fewer opposition figures will join the race due to the revamp of voting methods and the establishment of the Candidate Eligibility Review Committee.

In past elections, the Returning Officer had responsibility for validating candidates. However, the Returning Officer had limited power, which led to flaws in the vetting process and allowed many "Hong Kong independence" separatists to be elected, said Zhang Jian, director of the Hong Kong and Macao research section of the Shanghai Institute of International Studies. "The Candidate Eligibility Review Committee plays a key role as a gatekeeper," he added.

Tian Feilong, an associate professor at Beihang University's Law School in Beijing, said the new vetting committee excludes "extreme anti-China disrupters" as candidates. It only disqualified one candidate this year－Cheng Chung-tai, who was convicted and fined for the offense of flag desecration in 2017.

Tian said the reason why many opposition figures chose not to run in the election was that they were well aware of their past anti-China and troublemaking behavior. "They didn't have the confidence in passing the qualification test," he said.

Another reason is that the opposition camp has a "burn with us" mindset and wants to undermine the new electoral system by being uncooperative, he added.

According to a number of public opinion polls in Hong Kong, more than 70 percent of the public support the new electoral system and believe that the election can represent the overall interests of Hong Kong society, he said.

"The election on Sunday is an opportunity to test public opinion so that the new system can be implemented in Hong Kong and become a reliable institutional foundation for Hong Kong's democracy," he added.