Jim and Cathy McDougall, Michael Macintosh, Michael Watter and Harry Speath at the launch of International Missing Children’s Day in Canberra. Picture: Ky Smith

His children are among a rising number of Australian kids being abducted by one of their own parents. They’ve been missing for two and a half years now.

Today, on International Missing Children’s Day, he broke down as he recalled the day they disappeared.

Five-year-old Serena Speath.Source:Supplied

Thomas Speath at age four.Source:Supplied

Tom, then aged four, had been distraught. His father couldn’t work out why. Serena was also acting strangely, running around, jumping from activity to activity.

Then the doorbell rang.

Tom broke down crying and Serena snapped to a stop, put her shoes on and got ready to go.

The moment sticks in Harry’s mind now they’re gone. His children were only supposed to be visiting their mum for a few days.

“It’s like as if they’ve disappeared off the face of the planet,” Mr Speath said.

Today he was given another chance to find them.

Experts at the National Center for Missing and Exploited Children in the United States have created a photo manipulation of what they would look like now, aged seven and eight.

Harry Speath with the age-processed images of his children that were abducted by their mother. Picture: Kym Smith.Source:News Corp Australia

It’s part of a bid to get the message out about what Australian Federal Police acting commissioner Debbie Platz calls a growing problem for the county.

“Because of the climate that we live in and the extraordinary stress that many families are under, we are seeing a rise in parental abduction cases of children,” she said today.

“Investigations are incredibly difficult.

“What makes them complicated is that the parent who takes the child will often be travelling, have high mobility, they might change the child’s appearance, their name, the children are constantly changing schools.

“It has a really detrimental affect on the child.

“And because they don’t make social connections and friends that makes it all the more harder for us to be able to trace the children.”

Launching International Missing Children’s Day in Canberra today, Federal Justice Minister Michael Keenan said it was “vitally important” to get the message out about missing children.

“One parent who does not know the fate of their children is one too many,” he said.

Michael Macintosh, whose son Mathieu-Pierre was last seen in 2013 when his mum took him to France, had one message for other parents going through the same pain: “hang in there”.

Michael Macintosh with an image of his son that is age-progressed, to illustrate what he may look like today at the launch of International Missing Children’s Day. Picture: Kym SmithSource:News Corp Australia

“You go through many emotions,” he said.

“You go through a bit of frustration, anger, pain and eventually there’s some sort of acceptance and you move on in the hope that you eventually find your child.”

Mathieu-Pierre, aged nine when he disappeared, is believed to be living in France or Belgium. An image of him at age 13 was one of several other photo manipulations created by experts in the US, along with Isabella and Bronte Watter, who disappeared in April 2014 from Townsville, and Leela McDougall, who was last seen in Nannup, WA, in 2007. She would be 15-years-old now.

An age-progressed image of Isabella Watter at age 10. Picture: Australian Federal PoliceSource:AAP

Bronte Watter was abducted by Michael Watter’s ex-wife. Picture: Australian Federal PoliceSource:AAP

Twins Bronte and Isabella Watter were dropped off at school and have never been seen since by their father Michael.Source:The Courier-Mail

Leela McDougall was aged six when she and her mother disappeared in 2007. Picture: Australian Federal PoliceSource:AAP

Leela was last seen with her mother Chantelle. A note on the front door said ‘Gone to Brazil’.Source:Supplied

Anyone with information on a missing person is urged to call Crime Stoppers on 1800 333 000.