A man has been denied bail after being charged with the assault of a two-year-old girl who was found unresponsive in a car on a Sydney street.

The girl was found in a vehicle on McCredie Road at West Guildford on Monday afternoon following a report to police, officers said.

The toddler remains in a critical condition in Westmead Hospital.

Police allege the child was assaulted by her mother’s de facto partner, and the mother had driven her child away from the scene to a relative’s house in Guildford West.

Speaking outside Granville police station, Detective Acting Superintendent Glen Parks said a 23-year-old man had been charged with reckless assault causing grievous bodily harm.

“We will be alleging that there was a physical assault,” he said.

He did not reveal the exact nature of the child’s injuries.

“That is not something I can go into at this particular time but we are working to identify the exact injuries caused,” Acting Superintendent Parks said.

It has not been confirmed if a weapon was used in the assault.

Acting Superintendent Parks described the case as shocking for the community and for the police.

“It’s a human instinct to care for the young and the vulnerable and when incidents like this do occur it’s often very difficult to comprehend.”

Acting Superintendent Parks said the couple had been living together.

“The accused has only known the victim for a short period of time but at that time of the incident they were living together,” he said.

“Whilst a male has been arrested and charged in relation to this matter police are continuing their investigations and are urging any members of the community or family that may assist us with the investigation to contact Crime Stoppers or Granville police station.”

The man’s case was heard at Parramatta Local Court but he was not required to appear.

There was no request for bail and it was formally refused.

He will return to court next month.