Ben was just 21 months old when he went missing while on a family holiday on the Greek island of Kos in July, 1991.
Now it has been claimed that Greek detectives examining the disappearance are looking at possible explanations ranging from ‘serious crime to accidental death’.
But the lack of clarity has been ‘damaging to the credibility’ of the investigation in Greece, according to documents obtained by the Sunday People.
Specific details of the hypotheses have been blacked out in the papers according to reports
News of the theories emerged after a Freedom of Information request following a British review which took place earlier this year.
Ben’s family have always said they believe he was abducted after he disappeared from outside a farmhouse they were helping to renovate.
Earlier this year, South Yorkshire Police was granted £700,000 in Home Office funding to support the Greek authorities in continuing inquiries to find Ben.
A review was launched in February by Her Majesty’s Inspectorate of Constabulary to see how South Yorkshire officers would use the cash.
Papers from the review said enquiries had been made ‘across the world from Germany to Australia’.
In May Ms Needham travelled to Athens with South Yorkshire Police to appear on a missing persons programme and appeal for information.
There was excitement soon after when a man called the show saying he was Ben. But detectives ruled him out after discovering the caller had been DNA-tested several years ago and found not to be the missing boy from Sheffield.
Ms Needham begged police to visit the ‘strange little town’ where the gipsies lived for years after being told of numerous sightings of a child matching Ben’s description with the family.
In July 2015, police reveal they have questioned a Roma gipsy family in connection with Ben’s abduction.
Detective Inspector Jon Cousins said this was ‘significant’ to the investigation.
Police were also given the name of another man who had been previously ruled out, but said in May they were analysing a photograph sent to them of a third man. They were also chasing seven new leads at the time.
After the broadcast, she said: ‘I believe he is out there and I don’t think it’s going to be long. It’s just a feeling I have inside myself.
‘It feels like he is saying, “Come on, I’m here just come and get me.”
‘That keeps me going. I want him to know that I love him just as much today as when he was born.’
A spokesman for the Foreign Office previously said: ‘We have the deepest sympathies with Ben Needham’s family and continue to offer them consular support.
‘We are following this case closely and will fully assist South Yorkshire Police wherever possible.’
Ben vanished after travelling to Kos with his mother and grandparents, who were renovating a farmhouse in the village of Iraklise.
In 2013, a DNA test carried out on a man in Cyprus proved he was not Ben.