India on Tuesday asked Pakistan to release death row prisoner Sarabjit Singh as the Home Secretaries of the two countries held talks in Islamabad [Images] on terrorism and security and signed a pact to curb drug smuggling.

The demand for the release of Sarabjit, an Indian national languishing on death row since he was convicted of alleged involvement in four bomb blasts in Punjab province in 1990, was raised by Home Secretary Madhukar Gupta, sources said.

"Talks are continuing on the issue of Sarabjit. There has been no decision as yet," a senior Indian official told PTI.

Sarabjit's execution was put off indefinitely following Pakistani Prime Minister Yousuf Raza Gilani's [Images] intervention in May.

During the talks which were extended till Wednesday, senior Indian and Pakistani officials signed a memorandum of understanding on "drug demand reduction and prevention of illicit trafficking in narcotic drugs/psychotropic substances and related matters," said Indian High Commission spokesman Sanjay Mathur.

Sources said the agreement will enable the sharing of information between the anti-narcotics forces of the two countries.

The two countries also agreed that the main source of narcotics in the region continued to be Afghanistan, from where drugs are trafficked to India and Pakistan, the sources said.

The talks between the Indian delegation led by Gupta and the Pakistani side headed by Interior Secretary Syed Kamal Shah, being held as part of the fifth round of the composite dialogue process, will continue on Wednesday morning. Earlier, the talks were scheduled to conclude today.

Besides drug trafficking and the issue of Sarabjit, the two sides took up counter-terrorism, the release of prisoners being held in each other's jails and the liberalisation of the existing visa regime, officials said.

Even as the talks got underway in Islamabad, Pakistani authorities freed 99 Indian fishermen and two other prisoners from two jails in the southern port city of Karachi as a goodwill gesture.

These prisoners are expected to be repatriated through the Wagah land border on Wednesday. Pakistani officials had earlier indicated that they planned to raise recent reports about the alleged involvement of Hindu radical elements in last year's bombing of the Samjhauta Express train during the talks.

Nearly 70 people, a majority of them Pakistanis, were killed in that terrorist attack. It was not immediately known if this matter figured in today's parleys.

The last meeting of the Home Secretaries of India and Pakistan was held in New Delhi [Images] in July 2007. During those talks, the two sides had discussed drafts of revised visa and consular access agreements aimed at liberalising and making existing provisions more effective.

The agreement on granting consular access to prisoners in jails of the two countries was signed during External Affairs Minister Pranab Mukherjee's visit to Islamabad in May.

Terrorism [Images] and drug trafficking are among the eight items included in the composite dialogue process. The other issues are the military standoff on the Siachen glacier, Tulbul navigation project-Wullar barrage, the Sir Creek boundary dispute, economic and commercial cooperation and friendly exchanges, peace and security and the Kashmir issue.