Prime Minister Harper is heralding a new era in Canada-India relations with the signing of a nuclear co-operation deal between the two countries.

Harper signed the agreement on Sunday with Indian Prime Minister Manmohan Singh who was in Toronto for the G20 summit. It allows for uranium exports to India and technological exchanges that could be worth billions to Canada's nuclear industry.

The deal ends decades of chill over India's acquisition of a nuclear bomb. Harper said he believed India's Cold War duplicity has been consigned to history and that it won't use Canadian uranium to build nuclear weapons.

It's a landmark moment for Canada, which angrily stopped nuclear co-operation with India in 1974 after the government used plutonium from a Canadian reactor to build an atomic bomb. Singh pledged India will play by the rules this time.

India's nuclear program spurred Pakistan to develop its own nuclear bomb, escalating their already tense relationship.