Katju, who had earlier also appealed for Singh's release, made his latest request in a letter to Senator Syed Faseih Iqbal, a member of the Press Council of Pakistan.
In his letter, Katju said people in India were happy over the release of Pakistani prisoner Dr Khalil Chishty, who was lodged in an Ajmer jail and requested that people in Pakistan should do something about Sarabjit's case.
"In my opinion the prestige of Pakistan will go up if he is released and sent back to India. That will also help in improving the vitiated atmosphere in our countries," he wrote.
Katju also wrote that the basis of Sarabjit Singh's conviction in the Lahore bomb blast of 1990 was weak.
"I was going through some details of his case and found that the main prosecution witness, Shaukat Salim, later in a taped statement retracted his statement in Court and said that it was given under police pressure," he said.
"The other evidence against him is said to be his alleged confession, but we all know how confessions are obtained in both our countries (by third degree methods)," he added.
Katju said that in his opinion Sarabjit may have gone to Pakistan to do some illegal business but was not involved in the Lahore bomb blast of 1990.
"Unfortunately the atmosphere in both our countries is so vitiated that often we regard people of each other's countries as devils, and both Dr Chishty and Sarabjit were victims of this mindset," Katju wrote.
He also said that his three appeals for Sarabjit Singh's release to Pakistan President Asif Ali Zardari had extracted no response.
