New Delhi, Nov 01 (ANI): Bharatiya Janata Party (BJP) Vice-President Balbir Punj on Friday hit back at Communications and IT Minister Kapil Sibal for challenging his party's prime ministerial candidate Narendra Modi to a debate, and said that the opposition does not take challenges put by non-serious players of the Congress seriously. Punj said Sibal's challenge is a non-serious offer because only Congress President Sonia Gandhi and her son party's Vice-President Rahul Gandhi are of importance in the ruling party. Sibal earlier in the day criticized Modi for repeatedly raising slogans of a 'Congress free India, and challenged him to a debate on any issue of national interest.