With the rescue attempt stretching into the afternoon, authorities remained unable to say how many people were working at the time in a country where informal labour is common.
Four women were among the deceased.
The Chinese embassy in Phnom Penh has expressed its condolences over the incident and pledged to carry out a thorough investigation into the cause of the collapse and the role played by the three Chinese citizens involved.
The building was being put up in the thriving seaside resort town of Sihanoukville, which has several such Chinese-funded projects.
Provincial authorities said as of Sunday afternoon, half of the debris at the site had been cleared.
One, Ek Tha, who managed a team of 15 people cementing bathroom tiles and painting walls said 12 of his crew members were still missing.
Numerous buildings catering to Chinese tourists have been constructed in the region over the past few years, including dozens of casinos, according to BBC News.
"I heard the sound of rescuers, I called for help but they didn't hear me", Ros Sitha, one of the two found alive on Monday, told AFP.
The Chinese embassy said three of them were Chinese nationals.
Prime Minister Samdech Techo Hun Sen on June 24 appointed senior minister in charge of special mission Kun Kim as first Vice-President of the National Committee for Disaster Management, replacing Nhim Vanda.
Spokesman Kheang Phearum of Preah Sihanouk province told RFA's Khmer Service that about 1,000 rescuers were picking through piles of bricks and debris of the seven-storey building, which held an estimated 70 people when it collapsed early Saturday.
Cambodia has notoriously lax labour laws, putting construction workers at risk.
Twenty-four others were injured in the total collapse, which will heighten concern over unregulated construction as Chinese cash fuels a building blitz of hotels and casinos at this once-sleepy fishing village.