Anna Hazare has threatened to go on another fast in a letter sent to the PM, Sonia Gandhi and Law Minister Salman Khurshid..Anna has written if the Jan Lokpal Bill is not passed in the winter session of Parliament..he will launch another fast..In a 2-page letter..the anti-graft crusader has clearly sent out a warning of another anshan if the PM does not stick to his word of passing a strong Lokpal Bill..