When Mark Zuckerberg Met Narendra Modi - in a Suit and Tie

Earlier in the day, the Facebook co-founder also met Information Technology Minister Ravi Shankar Prasad as part of the Centre's ambitious Digital India plan which seeks to expand internet access across the nation.

"Mark's interest in India impressed me. Facebook wants to work with the Digital India program and the Indian govt is happy to support them in their launch of internet.org," Prasad said.

Zuckerberg was in the national capital to attend the two-day Internet.org Summit, where he said access to internet should be considered a human right. The 30-year-old billionaire is the third high-profile head of a US-based tech firm to visit India in the last few weeks, after Satya Nadella of Microsoft and Jeff Bezos of Amazon.

Zuckerberg's visit came three months after Sheryl Sandberg, chief operating officer of the social networking giant, visited India, Facebook's second biggest market. Sandberg had also met Modi.

Modi has over two crore fans on Facebook, making him the second most popular politician on the social networking site after US President Barack Obama. But it is the more discerning Twitter where Modi has a star-like presence.

One of the most popular men on Twitter, Modi has nearly seven million followers there. Add another three million followers of the @PMOIndia handle, and you have close to a crore and growing Modi followers in India and abroad.

Modi's formidable presence in social media is a part of the BJP's strategy of bypassing traditional media and reaching the supporters directly, a plank that worked for him and his party in the last Lok Sabha elections, giving the BJP a spectacular victory.

Since assuming power, Modi continued with what some call his Twitter diplomacy which included reaching out to global leaders through the microblogging site, sometimes in their language. The Modi effect saw most of his ministers, who were not on Twitter earlier, now actively tweeting.