The Indian prime minister has cancelled a meeting with a village boy who was reported to have won an international examination organised by Nasa.
Saurabh Singh would not speak to the press on Wednesday
It had been widely reported that 17-year-old Saurabh Singh had beaten 200,000 students in the examination.
The reports said President APJ Kalam had passed the same test.
However, Mr Kalam's office has denied that he had ever taken the exam. Nasa officials say they are unaware of any such exam.
The news of the boy's examination success had been reported widely in the Indian media and on the BBC News website.
No comments to press
Doubts about the authenticity of the International Scientist Discovery examination appeared on the Indian website Rediff.com on Wednesday, shortly before Saurabh Singh was due to meet President Kalam in Delhi and be congratulated on his achievement.
Later on Wednesday, Nasa spokeswoman Debbie Rahn, who has worked for the agency for more than 30 years, told the BBC News website: "I have been unable to confirm that such an exam exists. I have checked all the appropriate offices in Nasa."
The president's spokesman, SM Khan, told the BBC that, contrary to widespread reports, President Kalam had never sat for such an examination.
Journalists were eagerly waiting to talk to the boy and his father after their 10-minute meeting with the president.
But Saurabh and his father refused to talk to the press and left in a car.
The two were also supposed to meet Indian Prime Minister Manmohan Singh later on Wednesday.
But the prime minister's press adviser Sanjaya Baru said that the meeting has been cancelled after the president's statement.
Saurabh Singh comes from the district of Ballia, a poor area of the northern state of Uttar Pradesh.
The Uttar Pradesh chief secretary VK Mittal told the BBC that the Ballia administrator had been asked to collect "all papers and certificates" of the "examination" from Sourabh.
"There is reasonable doubt about Sourabh's performance now," Mr Mittal said.
A teacher at Saurabh's school Hema Chandra in Ballia said that a local newspaper had first reported Saurabh's exam success.
"We contacted Saurabh immediately. He confirmed he had topped the examination."