The Tehelka tapes on corruption in defence deals are "original" and not "overdubbed," a London-based expert said today.

Mathew James Cass told the S N Phukan Commission of Inquiry in New Delhi that the tapes were "edited" but there was no technical evidence that they have been "overdubbed", as contended by Samata Party leader Jaya Jaitley as well as army officers who figure in the tapes.

"In my opinion, there is nothing to indicate the tapes supplied to me by the Commission are not the camera originals made at the time of the incidents depicted. There is significant evidence to support the contention that they are the camera orginals," said Cass, an associate director for the Department of Electronic Evidence and senior video, audio and imaging expert at the Bureau of Forensic Science, London.

Cass, who was asked to examine the tapes to establish their authenticity as camera originals and explain anomalies, if any, said the tapes had been "edited" but he could not say if it was done 'maliciously'.

The expert, in his 16-page report, said the audio was by and large consistent with the background.

"In all instances where over-dubbing of another voice is alleged, there is no evidence on a technical level to support the allegation. The voice in each case is consistent as is the background sound," he said.

Cass, who has also worked in the Thames Valley Police's Scientific Support Unit said he received the tapes for examination on June 5, 2003, and was also supplied with the broadcast tapes and the recording equipments, including the briefcase camera and tie cameras used by the portal in the exposé.

He said he was also instructed to address specific allegations by army officers Anil Sehgal, Iqbal Singh and P S K Choudhary as well as Jaitley and businessman R K Gupta -- all of whom had appeared in the tapes -- by comparing the final edited programme with the 'camera originals'.

Asked whether the editing was done 'maliciously,' Cass said, "Whether or not the context has changed due to the editing is for the Commission to decide. I can only indicate to the Commission that an edit has happened."

He, however, recommended to the Commission that it should view the original tape on high quality playback equipment to make its own decision on whether the material removed in the edit was significant and if its removal does indeed change the context of the subjects, words or actions.

Maintaining that there were 'inconsistencies' in both the Commission's and news portal's transcription, Cass said, "I can point out the inaccuracies but it is not my place to comment on the change in context that these could result in."