Yoga guru Baba Ramdev on Sunday said that Prime Minister Manmohan Singh has written a letter to him,ahead of the fast he was launching next month in Delhi,against corruption. "PM has displayed a constructive stand and agreed upon his demands in his letter," Ramdev told reporters refusing to divulge contents of the letter. He claimed that about one lakh people would join him in fast while about one crore across the country would participate in his satyagraha intended against the scourge of corruption. The Yoga guru did not to comment on the remark made by the Congress general secretary Digvijay Singh that the former's fast was a 'stunt' and would ultimately turn out to be a flop. Ramdev is planning to launch the nationwide protest against the issues of corruption and black money stashed in foreign banks from June 4 at Ramleela Maidan in Delhi.