The men were intercepted in the Torres Strait in Australia's north.
The Sydney Morning Herald said they set foot last week on Saibai island, which would make it the first successful boat to reach Australian shores in nearly three years. Authorities in the country refused to confirm the group made landfall.
Only Monday the government trumpeted its success in preventing any migrants from arriving by boat in more than 1,000 days.
"Recently the Australian Border Force located and detained six Chinese nationals who were attempting to illegally enter Australia," a department of immigration and border protection spokesman said.
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It said five of them had been returned to China while two, including the Papua New Guinean, were arrested and charged with people-smuggling.
"They have appeared in court and been remanded in custody. As the matter is before the court it would be inappropriate to comment further," added the spokesman.
Asylum-seekers who try to reach Australia by boat are either turned back or sent to remote camps in Nauru and on Papua New Guinea's Manus Island, where conditions have been widely criticised.
Since the tough measures were adopted, which the government says are essential to prevent deaths at sea, Australia has gone more than 1,000 days since the last asylum-seeker vessel reached its shores.
Under the previous Labor government, at least 1,200 people died trying to make Australia by boat between 2008 and 2013.
Almost 850 vessels carrying 51,798 asylum-seekers arrived between those dates, according to figures compiled by the Australian parliament.
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