In a four-page letter, he alleged that the government's behaviour was "not at all right" and asked why Singh changed his stand on Citizens' Charter despite giving a written assurance that it will be part of the Lokpal bill.
He said in the past few months, Singh was giving him assurances through letters that a strong Lokpal Bill will be passed in the Winter Session of Parliament.
Hazare said in the last one year, the government has given a lot of assurances on Lokpal Bill but every time they have betrayed the countrymen.
"We suspended all our agitations till Winter Session taking your word on face value. Reports published in media now says that the Winter Session will end on December 23. Will the Lokpal Bill be passed by then. We have doubts on this," he said.
"Despite your promises, if a strong, independent and effective bill is not passed in the session, I will be forced to sit on a fast from December 27. Jail Bharo agitation will start from December 30," he said.
Demanding bringing CBI'a anti-corruption wing under Lokpal and make it its investigative agency, he said it appeared that no government wants to give away the control over CBI for political reasons.
"Does it mean that Lokpal will not have an investigative agency. Without an investigative agency what will it do? Then it is better that we don't need a Lokpal," he said alleging irrespective of Congress or BJP, CBI was misused.
Hazare said he was surprised to see the Union Cabinet clearing a separate Citizens' Charter on December 13 when Parliament has already passed a resolution in which it is clearly mentioned that it will be under Lokpal.
"You (Singh) yourself have written to me and now why are you changing your stand and say that it will be sent to the Standing Committee. That will take another four months. Don't you think that people are being cheated and cheated," Hazare said.
The activist also pointed out the Parliamentary Standing Committee recommendations on appointment of search and selection committee for Lokpal were fraught with deficiencies as politicians play a major role in it.
Hazare alleged that Parliamentary Standing Committee chairman Abhishek Manu Singhvi insulted Parliament by not taking into cognisance the resolution passed by the House.
"Out of the three issues -- inclusion of lower bureaucracy, Citizens' Charter and state Lokayuktas, two of them have not been accepted. If a Standing Committee Chairman ignores Parliament's resolution, what is the future of our democracy," Hazare said in the letter.