Justice S Muralidhar also pulled up the investigating officer for "non-association of public witnesses" in the case during the trial and said that Delhi Police should have made "more serious efforts to record the names of the people who refuse to be part of the investigation".
In April 2010, the trial court had awarded five-year jail term to former Lance Naik Mohd Naseem after holding him guilty of various offences under the Official Secrets Act (OSA).
"In that view of the matter, no grounds have been made for interference with the impugned judgment dated April 7, 2010 passed by the learned trial Court," the judge said.
Naseem had come in appeal before the high court against the trial court decision, which had also imposed a cost of Rs 10,000 on the convict, besides his jail term.
The police had informed the court that Naseem was found in possession of a set of documents which were meant to be supplied to a Pakistan embassy official. The documents were termed as prejudicial to the safety, security and interest of the country.
Following his conviction in 2010, Naseem was dismissed from service.