As many as 641 Indians, including 436 fishermen, are languishing in different Pakistani jails. Replying a question, External Affairs Minister Pranab Mukherjee told Rajya Sabha that lists of prisoners exchanged by the two governments on March 31 were under study. A final list will be put before the Judicial Committee scheduled to meet next month in Islamabad for their review and decision.

He said the absence of consular access was making it difficult to determine the exact number of prisoners and the details of sentences awarded.

Mukherjee said India has consistently taken up the issue of Indians in custody in Pakistan at the highest level. In reply to another question, he said 74 missing defence personnel, including 54 since 1971, are believed to be in Pakistani jails.

"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," said the Minister.

"The prolonged incarceration of our nationals in jails in Pakistan is a matter of grave concern to the Government of India," he said.

Despite a chill in relations after Mumbai train bomb blasts and later cross-border Samjhuta Express bombings coincided with political instability in Pakistan, there has been a drastic increase in the number of Pakistani visitors to India.

External Affairs Minister Pranab Mukherjee told Rajya Sabha that Indian High Commission in Islamabad had issued 1,14,937 visas to Pakistani nationals during the year 2007. Just few years ago in 2003 it had issued just 8,000 visas.

In 2003, the High Commission had issued visas to 8,390 Pakistani nationals and the number went up by many times to 62,541 in 2004, 90,663 in 2005 and 92,334 in 2006.

Meanwhile, replying to another question, Mukherjee said there were 13 Indian fishermen in Sri Lankan custody for allegedly smuggling narcotics or for transporting Sri Lankan refugees.

He said there have been incidents of firing or apprehension of Indian fishermen by the Sri Lankan Navy in their waters.

"While it is important for our fishermen to respect the International Maritime Boundary Line, especially keeping in mind the ongoing operations in Sri Lanka, we have impressed on the Sri Lankan Navy to act with restraint and for our fishermen to be treated in a humane manner," he said.