The discovery of a Finnish passport for his daughter may have been the catalyst for a father who has been missing with his child for four days.

A NSW man may be missing with his four-year-old daughter after discovering his former partner might have been planning to move to Finland with the child.

Greg Hutchings and his daughter Eeva Dorendahl, 4, were last seen on Pottsville Road at Pottsville in northern NSW on Saturday.

Mr Hutchings had arranged to meet his former partner, Eeva’s mother, in Pottsville around midday but he never showed.

Mr Hutchings’ family have since revealed the 35-year-old may have been concerned Eeva was going to go overseas.

His sister, Sheri Hutchings, said the discovery of a Finnish passport was possibly the catalyst.

“Greg has lived and loved that little girl with the lightest of love and would never compromise her safety,” she wrote on her Facebook page.

“He has been concerned that Eeva’s mum might relocate them to Finland without Greg’s knowledge.

“His discovery of a secret Finnish passport for Eeva has probably been the catalyst for his hesitation in returning Eeva to her mum.”

Ms Hutchings said she had complete trust Eeva was safe, happy and very well cared for.

Police would not comment on whether a passport was a motive for the disappearance.

Emergency services, including jet skis and a police helicopter, continued the search for Mr Hutchings and Eeva around Pottsville on Tuesday.

Crews scoured waterways and beaches but could not find the missing pair.

Tweed Police Inspector Gary Cowan said the pair had camped in the area before.

“It’s an area where the dad and daughter have been camping before so if they have gone to ground for whatever reason, they’ve probably got food and water there,” he told the ABC on Tuesday.

The search is expected to continue throughout the night and into Wednesday.

It has been reported Eeva was due to return home to the Sunshine Coast with her mother after staying with Mr Hutchings in Pottsville.

Mr Hutchings is of Caucasian appearance, about 175cm tall, with short brown curly hair and of a thin build.

Police say he was last seen wearing a black long-sleeve shirt, grey trousers and carrying a black backpack.

Eeva is also of Caucasian appearance, with long blonde hair and blue eyes.

She was last seen wearing an oversized blue and white-coloured shirt and multicoloured board shorts.

Police are urging anyone with information about this incident to call Crime Stoppers on 1800 333 000.