Missing six-year-old found in Amsterdam

Almost three years after his son went missing, former NSW deputy fire chief Ken Thompson has learned the six-year-old boy is in Amsterdam.

Andrew Thompson was abducted by his mother, Melinda Stratton, on April 24, 2008.

The Australian Federal Police issued a warrant for Ms Stratton's arrest and Interpol managed to trace her to Frankfurt in Germany.

Leads then went cold, however, so Mr Thompson took early retirement to look for his son himself.

Following a massive campaign including a website with information about his son, and a 6500km cycle through Europe, Andrew has been found.

"I didn't know where in Europe he might be," Mr Thompson told Macquarie Radio from Amsterdam on Thursday morning, having just arrived in the city.

"I just knew Europe was the most likely place, so I decided I would do whatever I could do to raise public awareness to Andrew, and to some other kids who are missing in Europe as well, by riding a bicycle and just trying to generate as much media interest as I could in Andrew."

Fairfax reported on Thursday that a school principal in northern Europe became suspicious after noticing Andrew's passport had expired, following an attempt to enrol him at the school.

"I'm not quite sure what alerted the suspicion but the person then went on the internet and decided (to) do a search for missing children in Australia," Mr Thompson told Macquarie Radio.

"She very quickly came across the internet site for Andrew that we promoted and then she saw the scale of the effort that was put into finding Andrew, and contacted the police.

"I think things happened very quickly after that."

Mr Thompson believes Ms Stratton has been taken into police custody and that Andrew is with a foster family.

"He is safe. We'll hopefully now get him back to Australia and then Melinda and I can resume the process that needs to be resumed, that was started in 2008," he said.

- AAP