Police in northern India arrested a youth leader from the Hindu nationalist ruling party for posting anti-Muslim comments on social media after derogatory remarks by another party official about the Prophet Muhammad led to a diplomatic furore, officials said on Wednesday.

Harshit Srivastava, a youth leader from Prime Minister Narendra Modi's Bharatiya Janata Party, was arrested in Kanpur city following communal tensions last week during a protest by Muslims to denounce the anti-Islam comments.

"We arrested the local politician for...