An unknown number of international travellers arriving at Sydney airport on Sunday were given an outdated information sheet about coronavirus precautions, including incorrect advice they could immediately return to their workplaces.

Guardian Australia understands the information handouts, which were more than a week old, were given to passengers on at least two Air New Zealand flights that arrived in Sydney on Sunday afternoon.

All travellers returning to Australia from overseas must self-isolate for a period of 14 days, whether or not they feel unwell.

On Tuesday, the chief medical officer, Brendan Murphy, said people had been breaking self-isolation rules, including by “going to the chemist on the way home”.

But travellers say the up-to-date information being given out contains no specific advice about how isolation works; instead the paper factsheets advise people to visit a web link for details and to stay at home “if you become unwell”.

Travellers also give drastically inconsistent accounts of health screening practices and verbal advice from authorities at airports.

Suriya Black told Guardian Australia passengers on her Air New Zealand flight from Auckland to Sydney were given a printout of a factsheet that appeared to be weeks out of date. Airline staff told passengers over the loudspeaker the information was incorrect and they would have to self-isolate, but the airline did not take back the forms.

The forms said that if travellers were “returning from a country with a higher risk of Covid-19” they should monitor their health for two weeks.

“You can attend work unless you work in a setting with vulnerable people,” the sheet says.

It is unclear whether the error was made by the airline or Australian authorities.

Black said there was a lack of screening once she arrived at the airport. She was required to sign a declaration committing to a 14-day self-isolation, but was not given any information about how that should work.

“The only check was a man in scrubs and a mask yelling at us from a distance asking if we felt sick,” she said. “They seemed more concerned about my boots and hiking gear.”

Other travellers have said there was little clarification other than the form committing to self-isolate.

“The signed form was to be handed in a passport control and we did this with no questions whatsoever and then we were let through,” said Tom Budge, who came back through Sydney on Saturday.

“It was like it was just for legal reasons, not about actually finding out whether you’re a carrier that needs to be more careful.”

Budge said passengers on his flight had been coughing and were obviously ill, but did not declare so when asked by airline staff.

“Duty-free was open so all the various different flights arriving could all mingle together.

“I saw no one screened, no random temperature tests. Nothing. Zero.”

“[People will] probably decide not to follow the rules, just like they were flouted on the plane.”

Air New Zealand, the Australian Border Force and the Australian Department of Health, which supplies the advice sheets, were approached for comment.