Police in Sicily on Wednesday discovered human remains they suspect is a four-year-old boy who went missing over two weeks ago in suspicious circumstances, reports said.

Volunteers have been combing woods near the town of Caronia on Sicily's northern coast for Gioele Mondello, whose disappearance has gripped Italy.

"(We're) nearly sure it's the body of Gioele," unnamed police investigators told Il Corriere della Sera daily. 

"The trunk and a part of femur" uncovered were compatible with a four-year-old boy, police sources told Corriere. 

The discovery was made by a police officer on leave who was helping others search for the boy. 

Gioele's mother, 43-year-old DJ Viviana Parisi, was last seen on the morning of August 3 climbing over a motorway barrier after a minor collision. 

Although cameras showed Gioele in the car earlier, witnesses gave diverging statements on whether Parisi was carrying her son with her when she climbed over the barrier. 

Her body was found five days later in a nearby forest close to Caronia, lying at the foot of a high-voltage pylon.

Prosecutor Angelo Cavallo - who has said his team was unable to rule out Parisi's accidental death, suicide or murder - was on the scene of Wednesday's discovery.

According to the pathologist, Parisi likely died where her body was found. It bore no visible wounds - though one arm was broken in several places - and the state of decomposition made it impossible to determine whether she was strangled.

Viviana and Gioele disappeared after the DJ told her husband she was going to Messina to buy shoes. She was not spotted shopping but her grey Opel Corsa was photographed on a slip road entering the motorway.