If you have any proof for that allegation, you should take it to court and have him tried. If not, you should not throw such allegations around so lightly. Such casual allegations have a very real negative effect, of demoralizing people and making them disaffected and frustrated with political institutions.
Please desist from casting allegations against people, no matte which politicial paty they belong to. And yes, it is a legal offence as well, called libel.
I say this not out of any love for Chidambaram - I would have said this if it was some other politician of some other party that you wee slandering. Because you see, it is very dangerous to create a negative mindset about politicians that in many cases is simply not true. Believe me, when BJP was in power, people used to do the same thing to their politicians as well. It is a nasty habit with real consequences for society.
The burden of proof is on the prosecution to prove guilt, not for the defence to prove innocence.