A Sydney father had hired a boat on the Parramatta River multiple times in the week before his body was found alongside his six-year-old daughter, police have revealed.

The pair had taken a rented boat out on the water near Concord in the city's inner west on Saturday.

After reports a body had been spotted in the water, emergency services found a 47-year-old man, who cannot be legally identified, floating just before midday.

He was pulled onto the hire boat but could not be resuscitated and died at the scene, police said. 

Hours later, at 5.30pm, officers recovered the body of a six-year-old girl, believed to be his daughter, from the river. 

Police sources told The Sydney Morning Herald on Sunday that the man is believed to have hired a boat several times over the past week, including with his wife on one occasion.

Investigators believe the man used the trips to plan an alleged murder-suicide, they said. 

The sources alleged CCTV from a nearby waterfront property captured the man throwing the girl overboard before jumping into the river himself. They also claimed neither could swim. 

Police divers recovered the girl's body from the riverbed after searching for almost seven hours after allegedly using the CCTV footage to help identify the location. 

A resident, who was down by the water with her toddler on Sunday morning, told the Daily Mail she was horrified by the tragedy.

She said it was very unnerving considering how quiet the area is and how great it is for families.

NSW Police told the Daily Mail the man was not known to authorities and there were no AVOs in place. 

Superintendent Christine McDonald said the man hired the boat just hours before the incident.

'We do know that the man that we've located hired the vessel today, and that is all forming part of our inquiries,' she told reporters on Saturday afternoon.

'Today [Saturday] at 12.30pm, police received a call from a friend of the man to say that he had concerns for the child's welfare and the man's welfare.

'Unfortunately, police had located that man deceased just before 11.45am, so about an hour beforehand.'

The girl's mother is believed to have given a statement to detectives and is assisting with inquiries. She is not accused of any wrongdoing.

'This is an absolute tragedy for the family and the community on every level,' Supt McDonald said.

'Obviously a mother in this situation who knows that her husband is now deceased...it would rock any mother to the core.'

She said that a definite line of inquiry is whether the incident was deliberate, including if family violence was involved.

'There are several lines of inquiry currently under way,' she said.

'But can I say from the outset, this is an absolute tragedy for the family and the community on every level. We will leave no stone unturned.'

A search of the boat will also be carried out by police.

Anyone with information is urged to contact Burwood police or Crime Stoppers.

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beyondblue 1300 22 4636

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Men's Referral Service 1300 766 491