Strict fiscal discipline observed by the Centre and the states has forced India’s budget deficit to come down to its lowest in eight years, FM P. Chidambaram said at the India Investment Forum here.Both the central and states are observing strict fiscal discipline and as a result, the budget deficit was 4.1 per cent of GDP in the year ending March 31, 2005, he said pointing out that it was the lowest in eight years. It was ‘‘less than 4.5 per cent estimated by the government in February.’’