But Liljana King is lucky to be alive after ingesting three tiny but powerful magnets one at a time.

Once they had all been swallowed, the 1cm-wide devices clamped together and tore six holes in the three-year-old's small intestine and two holes in the small intestine's blood supply.

Liljana played happily with her sisters in the backyard of their Macgregor home this week, having almost forgotten the drama which occurred in early June.

When Liljana complained of feeling unwell on a Sunday, her mother, Sarah Schwalm, assumed she had a stomach bug.

Early the following Friday morning Liljana's condition deteriorated and her parents took her to Calvary Hospital.

An X-ray revealed a foreign object and Liljana confessed to swallowing the magnets. Further scans showed stomach contents were freely floating around her abdomen. During exploratory surgery, surgeons at the Canberra Hospital eliminated infection, closed ruptures in the intestine and repaired the holes in the blood supply.

Paediatric surgeon George Malecky said Liljana would have died within 12 to 24 hours if treatment had been delayed.

''She had established peritonitis, which is a consequence, for example, of untreated appendicitis and is uniformly fatal,'' he said.

Liljana's father, Jacob King, used to manufacture magnets for therapeutic underlay blankets.

Ms Schwalm said the family used the magnets at home to stick Liljana and her sisters' artwork on to the fridge.

''She's a pretty smart little girl and she knows not to put money in her mouth and it would never occur to me that she would swallow magnets,'' Ms Schwalm said.

While the case was extremely rare, Dr Malecky said parents should be aware of the risks to young children of swallowing objects such as batteries and fishing sinkers.

The sinkers contained lead which quickly dissolved inside the stomach.

Dr Malecky said he had performed at least five procedures this year to remove batteries from children's stomachs.

Once inside the gut, corrosion was accelerated, releasing the battery's toxic contents.

Young children tended to swallow smaller batteries such as those used in watches.

''Parents need to be quite obsessive about the fact the battery stays in the device,'' Dr Malecky said.

''Don't buy a spare battery until you need one or if you do buy a spare battery, keep it locked up.''