Tokyo: Portraying India as a profitable investment destination which will require fund inflows to the tune of US$ 500 billion over the next five years, Prime Minister Manmohan Singh today invited Japanese companies to seize the opportunity with an assurance that "all legitimate concerns" of investors are being addressed.

He asked Japanese companies to regain their country's 'historic status of being the most important business partner of India by participating in public-private partnership and outlined various measures undertaken by the government to ease investments, like creating provision for grant assistance through a specially-created 'viability gap funding'.

Addressing Japanese business leaders here, he said India was witnessing high economic growth in which Japan should participate as the economic relations between the two countries presently fall short of potential.

"An economically-resurgent India offers a variety of investment opportunities, both in traditional and new sectors, in labour-intensive and knowledge-based industries," said Singh, who is here on a four-day visit since Wednesday.

He said a government estimate has projected that India needs investment of at least US$ 320 billion in the next five years in infrastructure alone and the total investment required would be closer to USD 500 billion.

"This requires public and private, domestic and foreign participation in the sector," he said.

"We happily welcome foreign investment and seek to promote public-private partnership," he said.