India has postponed peace talks with Pakistan after alleging that Pakistan-linked Islamic militants may have had a role in the Mumbai train bombings.
Pakistan has denied any connection to the bombings that killed more than 180 people in Mumbai last Tuesday.
The two sides were to meet in New Delhi this week to review progress in the peace process launched in 2004.
Indian Prime Minister Manmohan Singh says he will urge leaders of the Group of Eight nations meeting in St. Petersburg, Russia, to adopt a policy of "zero tolerance" towards terrorism.
The Press Trust of India new agency quotes Singh as saying he also will demand a "firm commitment" and action from Pakistan to make sure its territory not be used to stage attacks against India.
The Indian prime minister said the international community must isolate and condemn terrorists wherever they attack, whatever their cause and whichever country or group provides them sustenance and support.