A four year-old boy and his six year-old sister who vanished from their home three days ago are feared to have been abducted. 

Jack Sullivan and his sister Lily were last seen about 10am on Friday on a road close to their home in Lansdowne Station, Nova Scotia.

Their stepfather Daniel Martell believes the youngsters went out a sliding back door of the family’s home while he and the children’s mother Malehya Brooks-Murray fed their baby.

Martell told CBC News on Sunday that he was frightened the children were taken by a stranger.

He pleaded with the Royal Canadian Mounted Police to monitor the border with neighboring New Brunswick and nearby airports in case someone is trying to escape with them.

RCMP Corporal Sally Rice told CTV News on Saturday that there ‘is no information to suggest [the siblings] were abducted’.

‘Based on what we know, it appears they wandered off,’ she added.

Four year-old Jack Sullivan has been missing from his Nova Scotia home since Friday

Jack vanished alongside his sister Lily, six. The children’s stepdad Daniel Martell fears they were abducted, although a Royal Canadian Mounted Police spokesperson says they believe the youngsters wandered off. A nearby woodland is being searched

‘The search will continue until we receive any new evidence that changes our direction.’

A 3.5 kilometer (2.2 mile) radius has been set up around the nearby Pictou County Forest, with searchers focusing their efforts there.

Hauntingly, they’re tying ribbons to trees to note which areas have been searched.

The children’s mother Malehya Brooks-Murray begged for their safe return Saturday.

‘I’m just staying as hopeful as possible,’ she told CTV News.

‘I want them home. I want to hold them, and I want them home. When they’re found it will be the biggest relief to hug them.’

A huge search operation including drones, a helicopter and around 160 emergency service personnel has been deployed to find Jack and Lily.

The eerie disappearance has rocked the Canadian province of Nova Scotia, famed for beauty spots including Lunenberg (pictured)

The children’s mother Malehya Brooks-Murray has pleaded for their safe return

A drone, a helicopter and around 160 emergency services personnel have been drafted in to look for the missing children

‘Ground search and rescue team members and officers who were on scene overnight have been relieved by new volunteers and officers from agencies involved to allow for refreshed searches to continue as necessary,’ RCMP said.

Jack is described as having shortish blond hair. He was wearing blue dinosaur boots.

Lily has light brown, shoulder-length hair with bangs. She may be wearing a pink sweater, pink pants, pink boots and may be toting a white backpack.

Anyone with information on the missing children has been asked to contact Pictou County District RCMP or Crime Stoppers Canada.