The body of a man — believed to be aged in his 50s — has been found at Tweed Heads near the Queensland-New South Wales border, police say.

Key points: The man's body was found in a sleeping bag by a couple walking their dog

The man's body was found in a sleeping bag by a couple walking their dog Police say the man was found with "physical wounds"

Police say the man was found with "physical wounds" The man was carrying identification and police are working to contact his next of kin

NSW police said they were treating the death of the man found at the Jack Evans Boat Harbour park as suspicious.

The man's body was found in a sleeping bag by a couple walking their dog about 11:00am.

Detective Chief Inspector Brendon Cullen said the man was found with "physical wounds".

"I won't go into any description about those wounds, but he has suffered injuries," he said.

"The movements and the history of the victim is something that we are in the early stages of establishing.

"We are very keen to speak to any person that was in Jack Evans Boat Harbour yesterday evening and this morning who might have seen something or know anything about this.

"We do want to establish where this man is from and how he came to be in the state he is in now."

Authorities were alerted by a couple who had been walking their dog about 11:00am. ( ABC News: Tom Forbes )

Jack Evans Boat Harbour Park and surrounding bushland is an area that is well known for its homeless population.

"It certainly is an aspect we will be looking at in this investigation," Inspector Cullen said.

He said the man was carrying identification and police were working to contact his next of kin.

A crime scene has been established and detectives, including members of the Homicide Squad, are investigating.

Resident Kheloud O'Brian said the number of homeless people living in Tweed Heads was growing.

"There's always violence here, and it's often around drugs and alcohol, so they're constantly fighting each other most of the time," she said.

"There's more around — I met a 70-year-old [homeless] man the other day who had come from Bundaberg.

"Often they get pushed out, moved further out, and there's nothing for them or nowhere to go, so they just stick around where it is comfortable and familiar."

Last year, a nine-month-old baby girl was allegedly thrown into the water at Jack Evans Boat Harbour, and her body washed up on Surfers Paradise beach.

Her father was charged with murder.