Narendra Modi addresses a rally in Karnataka on Tuesday

A move to impose service tax on Narendra Modi 's rallies has added another notch to his ongoing war of words with Finance Minister P Chidambaram."I have realized on what issues the Honourable Finance minister is working very hard," Mr Modi said at an event in Gandhinagar today, adding, "I am happy that my rallies are now contributing to the revenue of the country."The Centre's notice asking the BJP to deposit service tax on revenues generated by Mr Modi's rallies was withdrawn last evening after angry reaction from the party.Mr Modi's acerbic remarks today referred to Mr Chidambaram's perceived swipe at him while presenting his interim budget on Monday: "My mother and Harvard taught me the value of hard work." ( Read more The minister was responding to Mr Modi's taunt at a rally in his home state Tamil Nadu, where he said that Mr Chidambaram had failed to revive the Indian economy despite his Harvard background.Hours later came Mr Modi's riposte. "It's up to the people to decide whether the economist PM and FM have been 'hard working' or Mr Chidambaram has for long been 'hardly working' in their tenure," he tweeted.Mr Chidambaram has for long been one of the Congress' most aggressive Modi-baiters. Mr Modi has pulled no punches either.

At the Chennai rally last week the BJP leader had said: "The Finance Minister is from Harvard. The Prime Minister is an economist and he too has a degree from a big university. I have hard work to my credit. Going to Harvard means nothing. What matters is hard work... A man who has just studied in an ordinary school, sold tea and has not even seen the doors of Harvard has shown what it takes to handle economy."