A man whose badly burned body was found at a popular picnic spot in Sydney’s southwest might have been killed elsewhere and dumped at the reserve, police say.

A council worker, who was preparing to open the gate at the Lambeth Street Reserve at Picnic Point, found the body on a roadway just after 5am on Monday.

The man’s burns were so severe efforts to identify him and his age have been difficult.

Police are calling for anyone with a loved one, colleague or friend missing to contact them.

Superintendent Dave Eardley confirmed the body had been burned.

“But other than saying it’s a male person, it’s very hard to expand on that at the moment,” he told reporters.

“We are hopeful we might be able to narrow down a time-frame when the person was brought here.”

Supt Eardley said police want to hear from anyone who noticed cars stopping or suspicious activity around Henry Lawson Drive during Sunday night.

“I think it would be fair to conclude that the body was brought here at some stage during the evening,” he said.

He confirmed one scenario would be someone carrying the body, which was found 50 metres inside the reserve boundary, to its leafy resting place.

Supt Eardley said he couldn’t fathom why someone would burn a body.

“Any time a person loses their life is a tragedy,” he said.

“This is compounded by the fact that someone has chosen then to do that to a body.

“I can’t fathom that, I don’t think any rational person in our community can make sense of that.”

Forensic experts will be brought in to help identify the man and welfare services will be provided to the council worker.

Nearby resident Sue Parmaxidis said she heard an explosion early on Monday morning.

“It was a loud noise and would have been from about 4.30am or 10 to five,” she told reporters.

“You could say it might have been an explosion, it was like a bang.”

Ms Parmaxidis said the reserve was popular with families and children.