Claiming that India is riding an "investment boom" whose growth has touched 57%, Finance Minister P Chidambaram today said this should be maintained for the next four to five years to sustain economic growth of 8 to 9%.India should welcome investments from any source - private, public or foreign, he said at "SPEED 2006 - conference on southern prosperity through enhanced economic development".Investments are needed for infrastructure development, which should keep pace with economic growth otherwise productivity would be affected as in the case of Tuticorin port, Chidambaram said.Many foreign investors were willing to invest in India because there was saturation of investments in their countries."They should be welcomed to develop this country," he said.Attributing the telecom sector's success in India to competition between the private and public sectors, he said if other industries were to succeed, there should be similar competition."Though the government has decontrolled and the licence raj has gone, a few departments are still controlled (by the government). I am not satisfied with the present investments by the private sector. They should be given more space in investments," he said.