Police hold grave fears for a toddler who has been missing for two days on an isolated far-north Queensland cattle station.

But the Cape Patrol Insp Mark Henderson said they would not give up trying to find two-year-old Ruben.

The boy went missing from his home on Koolatah station on Tuesday afternoon.

A massive search resumed at first light, when Henderson said light rain was making the search more difficult.

Seven helicopters and heat-seeking drones have been crisscrossing the 170,000-hectare station looking for signs of the boy as others searched on foot, horseback or motorbike. But by noon on Thursday there was still no sign.

“I guess it is coming to that time where the fears that we have for this young fellow start to become grave,” Henderson said via video.

“But we won’t stop … we will continue to try and reunite that child with their parents and grandparents.”

He said more resources were coming from Cairns to help the family – police, State Emergency Service crews and some 20 people from neighbouring properties.

Police divers were due to arrive on Thursday afternoon as the property backs onto a lagoon and the Mitchell River, east of Kowanyama, on the western side of Cape York peninsula.

The little boy’s mother, Natasha Scott, has spoken of her desperation on social media.

“As people may know my little Ruby has gone missing,” she wrote on Facebook on Wednesday.

“I have every person that can help helping to find him ... [I am] trying to hold myself together.”

Scott thanked everyone who had helped spread the message about her son and joined in to look for him.