"Another phase of the general elections begins today. I hope those voting today do so in large numbers and break the voting records of the previous three phases. A special appeal to young voters to head to the polling booth and exercise their franchise," Modi said in a tweet.
Voting began across 72 Lok Sabha constituencies spread over nine states, mostly in the Hindi heartland.
A total 12.79 crore people are eligible to vote in this phase covering 17 seats in Maharashtra, six in Odisha, 13 in Uttar Pradesh, five in Bihar, and eight in West Bengal, while Rajasthan, Jharkhand and Madhya Pradesh have their first phase of polls with voting in 13, three and six constituencies, respectively.
Voting will also be held in the second phase of the staggered polling in Jammu and Kashmir's Anantnag constituency.
In the fourth phase, the BJP will be defending 45 of the seats it won in the 2014 Lok Sabha battle -- 13 in Rajasthan, 12 in Uttar Pradesh, eight in Maharashtra, five in Madhya Pradesh, three in Bihar, three in Jharkhand and one in West Bengal.
The seven-phase Lok Sabha elections started on April 11 and would conclude on May 19. Counting of votes will take place on May 23.