UPDATE, 4.15PM: Detectives have released CCTV footage of a man who may be able to assist with their investigations into a "horrendous" sexual assault of a woman at a Townsville McDonald's restaurant.

Detective Inspector Chris Lawson, from Townsville Crime Services, said the 37-year-old woman was assaulted on Sunday between 4.30pm and 5.15pm at the Rasmussen store.

"It was an horrendous attack, it was the sort of attack you don't want to see in our community, and it's the sort of attack we are not prepared to accept within our community," Det-Insp Lawson said.

"People that have behaved in this manner need to be held accountable for their actions and brought before the court and be subject to the full force of the justice system."

He said the attack took place "within the toilet area of the restaurant".

Det-Insp Lawson said the suspect fled the restaurant on foot towards Alambie Lane.

The man is described as Aboriginal in appearance, around 163cms tall and was last seen wearing a black beanie, dark sunglasses, dark shorts and what is believed to be a jersey with the number 17 on the back.

He said police were alerted to the assault by the woman.

"Police received a call from the victim in the matter and subsequently sent the Sexual Crimes Unit from the Townsville Police District and also all the local resources," Det-Insp Lawson said.

Det Insp Lawson did not believe the alleged attacker knew the woman.

He said the woman spent the night in hospital but has since been released and offered support through the Sexual Crimes Unit.

"Our Sexual Crimes Unit has spoken with her but haven't obtained a formal statement at this point," he said.

Det-Insp Lawson appealed for CCTV footage from nearby businesses and any information from the public which could help police with the investigation.

"We will be working extremely hard and diligently towards identifying the person who was involved in this matter and making sure he is held accountable for those actions," he said.

A McDonald's spokeswoman said the store was assisting police.

If you have information for police, contact Policelink on 131 444 or Crime Stoppers on 1800 333 000 or via crimestoppersqld.com.au 24hrs per day. Quote this reference number: QP1802157406

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