Top former space scientists, all retired from ISRO on Wednesday slammed their former colleague S. Nambi Narayanan, terming the claims he has made in movie "Rocketry: The Nambi Effect" released globally on July 2 "a bluff" and "devoid of facts", and hence, making them decide to go public.

The movie is about the life and struggles of Nambi Narayanan who was a senior scientist in the ISRO and later was alleged of being involved in espionage. He fought the case, got acquitted of all charges, and even made the police pay him compensation for undue detention and trauma.

The film has been scripted and directed by actor R. Madhavan and has by now completed more than 50 days.

Among those who addressed the media here included Dr A.E. Muthunayagom, the former Director of ISRO's Liquid Propulsion Systems Centre (LPSC), D. Sasikumaran, former Deputy Director, Cryogenic Engine), Prof E.V.S Namboothiri, the former Project Director, Cryogenic Project, and a few others.

Muthunayagom claimed 90 per cent of what is said in the film is false.

"We have heard that Nambi has claimed in interviews after the film was released that all what's been told in the film is truth, but 90 per cent of what has been told is not true. Many former scientists after seeing the film has called up me and said all the credit has been taken by Nambi," he said.

"I have asked for certain details from the present Chairman of ISRO on the claims Nambi has made in the film about the cryogenic engine being brought from Tashkent. This is also false and once I get the details I have asked, I will take appropriate steps," Muthunayagom said.

He recalled that Nambi Narayanan had called him soon after he was awarded the Padma Bhushan award and "I asked him, how he managed it and he said as part of his case, he had developed some Delhi connections and it was because of that".

"He did not get the award for his contribution in ISRO, as the Space Department had not recommended it," said the scientist.

Nambi Narayanan worked under Muthunayagom for 26 years after joining service in 1968.

Among the other claims that was countered by the group of scientists includes the bluff that it was ace scientist Vikram Sarabhai who had sent Nambi Narayanan to Princeton University in the US for his Masters.

The claim that his arrest in the ISRO Spy case had led to a delay in the development of cryogenic engine causing a huge financial loss was not right, the scientists said, as when the work began on it in 1980s, Nambi Narayanan was not at all part of the team.