Ismail Samma, 51, a resident of Nana Dinara village some 50 kilometres from the Indo-Pakistan border in Gujarat's Kutch district, went missing in August 2008 as he strayed into the Pakistan side while grazing cattle, said Jatin Desai of the Mumbai-based NGO, Pakistan-India Peoples' Forum for Peace and Democracy.
Mr Desai, who filed an RTI on this issue in August last year with the Ministry of External Affairs, recently received a reply to it from the Indian High Commission in Pakistan.
Ismail Samma, arrested in Pakistan after he crossed the border, was sentenced to five years in jail for espionage in October, 2011, he said.
"His jail term ended in October, 2016. But due to lack of nationality verification on the part of the Ministry of Home Affairs, he has not yet been repatriated," Desai said.
While Samma's family had been looking for him for several years, it recently learnt that he was lodged in a jail in Pakistan.
A fellow villager, Rafiq Suleman, who had returned from a Pakistan jail, told the family he had seen Samma in a Karachi prison.
Mr Desai said Indian government officials knew about Samma's whereabouts from at least 2014, when he was provided consular access by the Indian High Commission in Pakistan.
It added, "However, the same is still awaited from the MHA due to which this Mission is unable to take up the case of release for Mr Mohammad Ismail with the Government of Pakistan."
The RTI reply also informed the petitioner that "there is no time limit for confirming nationality after the High Commission gets consular access."
Under an agreement signed between India and Pakistan, if a man is arrested across the border, he shall be given consular access within 90 days of his arrest. Once his nationality is verified, the process of expatriation is initiated.
"At times, the two countries do not follow the rules.
Since there is no time limit for nationality verification after consular access, Ismail, who was given consular access in February, 2014, is still in jail as his nationality has not been verified. It is inhuman," Mr Desai said.
"We need to see that nationality is verified within three months. The government needs to be more sensitive in such cases," he said.