Inquiry after body found in Sydney's north

An investigation is under way after a woman's body was found in bushland in Sydney's north.

The body of the woman, believed to be in her 30s, was found on a fire trail in Hornsby by two bushwalkers on Saturday afternoon.

The woman has not been formally identified and a post-mortem will be carried out on Monday to determine the cause of death.

Detective Inspector Frank Gilroy said a crime scene had been established and was being forensically examined.

"Shortly we will be deploying police in for a physical search of the area as well," he said on Sunday.

Police are not ruling out the possibility the woman was murdered and are appealing to the public for information.