"You have also witnessed the signing this morning of the agreement between India and Pakistan on reducing the risk of accidents relating to nuclear weapons."
The nuclear accord, which comes into force immediately, was the key confidence-building measure of the visit by Khurshid Kasuri, Pakistan's foreign minister, which began on Tuesday as part of efforts to resolve six decades of bloodshed over Kashmir.
No details were immediately available on how the agreement will work in practice. The two sides already exchange lists of nuclear facilities at the start of every year.
"It is a terrorist act, we should condemn this act with unity"
Farzan, Hyderabad, India
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Islamabad and New Delhi first put forward the idea for a nuclear weapon safeguard agreement in 1999, but a bloody conflict at Kargil in Kashmir intervened and it took until January 2004 for peace talks to be re-launched.
The countries held tit-for-tat nuclear weapons tests in May 1998 that led to international sanctions on both and fears they would consider the weapons as bargaining chips in the dispute over Kashmir which caused two of their three wars since independence in 1947.
Mukherjee and Kasuri held a press conference after the signing and answered questions centred on the attacks which killed 68 Pakistanis and Indians on a cross-border train on Monday after two bombs exploded and started a fire.
Similar attacks have in the past derailed the peace process.
Terrorism was expected to figure high on Wednesday's agenda, an Indian official said, after the bombing of the "Friendship Express" - a key transport link between the estranged neighbours.
The agreement titled Reducing the Risk from Accidents relating to Nuclear Weapons was signed by India's foreign ministry additional secretary KC Singh and his Pakistani counterpart Tariq Osman Hyder.