Ben was just 21 months old when he went missing on the Greek Island of Kos. Police believe he died on July 24, 1991, as a result of an accident involving heavy machinery.
The toddler was staying at his grandparents' farmhouse on the Greek Island when he vanished, but his mother has never stopped believing her son is still alive.
Ms Needham said: "Someone out there holds a very dark secret. You can not hide forever.
"There is no proof Ben died in an accident on July 24, 1991. Until such proof is forthcoming Ben is still a missing person and we urge anyone who knows anything to please do the right thing."
Ms Needham said that while there is no evidence to show her Ben is dead, she has to believe he is still alive.
She also revealed how she has devoted three decades to the search of her son with her main goal in life to find Ben.
The most high-profile investigations into Ben's disappearance only started around 20 years after he went missing, following a Home Office grant to South Yorkshire Police.
Operation Ben was formed in April 2015 with up to ten officers, including two who speak Greek, wrked on the case with total funding of around £1 million.
Further witnesses and people claiming to be Ben were interviewed and DNA samples taken, but no matches were made.
In September 2016, a second and final excavation of the farmhouse from where Ben went missing, along with another site nearby where it is believed a local digger driver used to dump debris.
South Yorkshire Police concluded Ben died on the day he went missing in an accident with a large mechanical digger.
A force spokesman said this week: "We continue to hold the view that Ben died as a result of a tragic accident on the day of his disappearance, however should any new viable line of inquiry come to light, we would seek to work with the Greek authorities to support them in their investigations.”
Today, the Needham family are asking people to light a candle for Ben and place it in view to "light the way home for Ben".
A Just Giving site has also been set up to raise £10,000 to offer as a reward for information leading to him.
Anyone wishing to donate can clickhere.