Many of those present had stayed overnight to guard supplies left over from the day before, when hundreds had gathered to "greet" travellers with anti-government brochures in a bid to win international support for the movement, the South China Morning Post reported.
The brochures explain the main demands of the movement, which erupted from opposition to the now-abandoned extradition bill, which would have allowed the transfer of criminal suspects to mainland China and other jurisdictions with which the city does not have an extradition agreement.
The demands include a full withdrawal of the draft legislation, implementation of universal suffrage and a retraction of the riot label attached to recent anti-bill protests.
Airport authorities had heightened security ahead of this mass sit-in protest, which began on Friday and will end on Sunday.
Meanwhile, energy levels were running low among the fewer than 100 protesters present. Many were sleeping on the floor in the arrivals hall on Saturday morning.
But organisers have said that more protesters would be arriving by 1 p.m.
On Friday, Beijing banned Hong Kong flag carrier Cathay Pacific from using aircrew on flights entering Chinese airspace who had been involved in anti-government protests, reports the South China Morning Post.
Two other rallies at the city's Tai Po and Wong Tai Sin were planned to take place later on Saturday.
But permits for the rallies were rejected by the police, and it remained unclear if they would be allowed.
The sit-in protest follows the cancellation of more than 250 flights as part of the citywide strike on Monday.
On July 26, an estimated 15,000 protesters gathered at the airport to try and win international support for the movement against the now-shelved extradition bill.
( With inputs from IANS )