A total of 641 Indians, including 436 fishermen, are languishing in different Pakistani jails, the government said on Thursday.
External Affairs Minister Pranab Mukherjee told Rajya Sabha while replying to a written question that the government has consistently taken up with Islamabad, including at the highest level, the issue of Indians in custody in Pakistan.
In reply to another question, he said 74 missing defence personnel, including 54 since 1971, are believed to be in Pakistani jails.
He said lists of prisoners have been exchanged by the two governments on March 31 and are under study.
"India expects the government of Pakistan to implement the recommendations of the Judicial Committee (comprising judges from India and Pakistan) to release and provide consular access to all detained fishermen and prisoners," Mukherjee said.
"The prolonged incarceration of our nationals in jails in Pakistan is a matter of grave concern to the government of India," he said.
Mukherjee said in the absence of consular access to many fishermen and other prisoners, it was not possible to determine the details of sentences awarded.