Condemning Tharoor's comment, the NCW also demanded that he should apologise for allegedly degrading the achievement of Chhillar.
Tharoor apologised over his remark, which, he said was a "light-hearted" comment and also praised Chhillar.
However, it was not clear if he apologised after the NCW took serious view of the tweet.
"What a mistake to demonetise our currency! BJP should have realised that Indian cash dominates the globe: look, even our Chhillar has become Miss World!," Tharoor said on the micro-blogging site, apparently punning on the word 'chillar', which in Hindi means "loose change"
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Accusing Tharoor of degrading the achievement of Chhillar, a medical student who hails from Haryana, the NCW asked whether the Congress leader will call his own daughter a "chillar".
"...he must apologise immediately," it said.
Tharoor apologised, stressing that no offence was meant to the "bright young girl".
"Guess the pun IS the lowest form of humour, & the bilingual pun lower still! Apologies to the many who seem to have been righteously offended by a light-hearted tweet today. Certainly no offence was meant to a bright young girl whose answer I've separately praised. Please: Chill!," he tweeted.