Police as well as Hong Kong's anti-corruption watchdog have launched investigations into the blaze at Wang Fuk Court, but a petition calling for greater accountability and demanding an independent probe was swiftly shut down as an organiser was reportedly arrested for sedition.

The first Sunday since the deadly inferno saw thousands flock to a small park next to the charred residential estate, which has become a focal point for grief over what was the world's deadliest residential building fire since 1980.

The queue of people, many dressed in dark colours and holding flowers, stretched more than 1.2 kilometres (0.75 miles) in the Tai Po neighbourhood, an AFP reporter saw, meaning some mourners had to wait hours to pay their respects.

Police said on Sunday that the death toll had risen to 146, up from 128 recorded the day before, as officers of the Disaster Victim Identification Unit broadened their search in the estate and recovered additional bodies.

"As of 4:00 pm (0800 GMT), the latest death toll stands at 146. We cannot rule out the possibility of further fatalities," Chief Superintendent Tsang Shuk-yin of the police's casualty enquiry unit told a news conference.

The 18 additional bodies were found in flats, staircases, hallways and rooftops, police said, adding that the wrecked building interiors complicated the search.

Hong Kong officials have set up an interdepartmental task force to look into the cause of the blaze.

The city's anti-corruption watchdog has arrested 11 people in connection to the fire, three of whom were also arrested by police for manslaughter.

Hong Kong media have widely reported, citing unnamed sources, that police have made one sedition arrest in relation to the fire.

Reports said the person arrested was 24-year-old student Miles Kwan, who was among those handing out flyers on Friday calling for governmental accountability and an independent probe.

Police told AFP on Saturday that it "will take actions according to actual circumstances and in accordance with the law" and said they had nothing further to add on Sunday evening.

Kwan could not be reached by phone on Sunday.

Beijing's national security arm in Hong Kong said on Saturday it staunchly supported the Hong Kong government in punishing acts by anti-China forces that "use disaster as pretext to cause chaos in Hong Kong".

- Dozens still missing -

Police said 54 of the 146 recovered bodies were yet to be identified. Officers were still trying to reach some 40 people who were reported to be missing.

Fourteen people injured in the fire remained hospitalised in critical condition, with another four in serious condition.

The Housing Department said it had surveyed six of the estate's eight apartment blocks and found "no immediate danger" to their overall structure.

Outside of the Tai Po neighbourhood, other parts of Hong Kong also saw events to mourn the fire victims, attended by many migrant domestic workers who had Sundays off.

Prayer events in the central business district and in Victoria Park drew more than 100 attendees each.

At least seven Indonesian nationals and one Philippine migrant worker had died in the fire, their respective consulates said separately on Saturday.

Hong Kong's Buildings Department has ordered temporary suspension of works on 30 private building projects across the city.

The Hong Kong Jockey Club meanwhile said Sunday's race meeting would be held behind closed doors and that the gross income of HK$70.2 million ($9 million) will be donated to a government-run relief fund.