"Obviously whatever is not permitted by US laws, will not be signed by US firms. Once the international civil nuclear trade opens up, India can sign contract with several countries," he said in reply to a question asked by a Mumbai school student.

Noting that the country has only 0.8 per cent of world's known oil and natural gas resources, Kalam said based on the progress visualised for the nation during the next two decades, the power generation capacity has to increase by to 400,000 MW by the year 2030 from the current 144,565 MW.

"Energy independence has to be achieved through three different sources -- renewable energy, electrical power from nuclear energy and bio-fuel for the transportation sector. Nuclear power generation has been given a thrust by the use of Uranium-based fuel," the former President said.

However, to meet the increased needs of nuclear power generation, it is essential to pursue the development of nuclear power using Thorium, reserves of which are higher in the country, technology development has to be accelerated for Thorium-based reactors, Kalam added.