"Anna should be wary of RSS' game to make him team up with Ramdev whose dealing in black money and money laundering stands exposed," Singh wrote on community micro-blogging site Twitter.
Welcoming the social activist's decision to part ways with the pro-politics group in the anti-corruption movement, he tweeted, "I congratulate Anna for realising the political ambitions of his team. He should continue his fight against corruption and for strong Janlokpal."
Earlier in the day, Kejriwal described Hazare's decision as "shocking and unbelievable" and said the veteran activist's principles will be the foundation of their party.
Hazare yesterday announced the split with Kejriwal-led group, which is going ahead with its plan to form a party, saying they should not use his name or photo for the outfit they are planning to launch.
Kejriwal supporters have taken potshots at Hazare on social networking sites like Twitter, posts which were re-tweeted by India Against Corruption.