By Laurie Chen, Fabian Hamacher and Joyce Zhou

HONG KONG, Dec 5 (Reuters) - Turnout is expected to be low for Hong Kong's "patriots only" legislative election on Sunday, with subdued political campaigning as the population reels from the city's deadliest blaze in decades that has killed 159 people so far.

Volunteers tentatively handed out flyers and hung banners outside subway stations and crowded intersections on Friday, but they were largely ignored by residents. Campaigning activities were suspended for a few days following last week's fire.

"This accident, of course, can influence the attendance of the election ... (Hong Kongers) don't have the interest, the eagerness to elect people," said C.K. Lau, an 82-year-old retiree.

The vote has been viewed by some analysts as a test of legitimacy for the Hong Kong government as it tries to soothe public anger over the fire and oversee an ongoing national security crackdown.

Locals said they were angry and traumatised after authorities admitted that substandard building materials used during renovation work at the high-rise estate in northern Tai Po district were responsible for fuelling the blaze.

"Everyone's mood is so heavy right now," said May Li, 48. "How can we still talk about holding an election under these circumstances? It definitely has to be postponed."

The last Legislative Council elections in 2021 recorded the lowest voter turnout - 30.2% - since the former British colony returned to Chinese rule in 1997.

On Thursday, Hong Kong's national security office urged residents to "actively participate in voting," saying it is critical in supporting government post-disaster reconstruction efforts.

"Every voter is a stakeholder in the homeland of Hong Kong," a statement said. "If you truly love Hong Kong, you will vote sincerely."

Four people were arrested for inciting others not to vote, the city's anti-corruption body said on Thursday. A further three were arrested for the same offence on November 20, according to a previous statement from the body.

National security authorities have also repeatedly warned against attempts to "exploit" the fire to incite another "colour revolution," referring to the 2019 pro-democracy protests that roiled the city.

Publicly inciting a vote boycott was criminalised in 2021 as part of sweeping electoral reforms that effectively squeezed out pro-democracy voices from the city's 90-seat legislature.

Coming after Beijing imposed a national security law on the city in 2020, the reforms ensured that only pro-Beijing candidates - "patriots" - could run and further reduced the space for meaningful democratic participation by Hong Kong residents, analysts say.

Pan-democrat voters - who traditionally made up about 60% of Hong Kong's electorate - have since shunned the elections.

The number of registered voters for Sunday's polls - 4.13 million - has also dropped for the fourth consecutive year since 2021, when a peak of 4.47 million people were registered.

The current term of the Legislative Council ends on December 31. If the election were delayed, a vacuum period could emerge, making it difficult to maintain a functional lawmaking body.

(Reporting by Laurie Chen; Editing by Thomas Derpinghaus)