Almost a billion people in the world's most populous nation are eligible to vote in the entire exercise running through the peak of summer until June 1, with results set, opens new tab for June 4.

Indians began voting on Friday in the world's largest election as Prime Minister Narendra Modi seeks a historic third term on the back of issues such as growth, welfare, Hindu nationalism and personal popularity.

The vote pits Modi's Bharatiya Janata Party (BJP) against an alliance of two dozen opposition parties that promise greater affirmative action and more handouts while stressing what they call the need to save democratic institutions.

"Modi will come back to power, because apart from the religious push, his other work, in areas such as safety and security, is good," said Abdul Sattar, 32, a Muslim voter in the city of Kairana in the most populous state of Uttar Pradesh.

He was among those queuing outside polling stations, some well before the opening time of 7:00 a.m. (0130 GMT), amid tight security.

Friday's phase is the first and largest of seven, covering 166 million voters in 102 constituencies across 21 states and territories, from Tamil Nadu in the south to Arunachal Pradesh on the Himalayan frontier with China.

Almost a billion people in the world's most populous nation are eligible to vote in the entire exercise running through the peak of summer until June 1, with results set, opens new tab for June 4.

Surveys suggest the BJP will easily win a majority even though voters worry about unemployment, inflation and rural distress in the world's fastest growing major economy.

Unemployment was the main concern for Mohammed Shabbir, another Muslim voter in Kairana, about 100 km (60 miles) from Delhi, the capital.

The 60-year-old driver and father of eight said none of his children had regular jobs.

"Even the Hindus are affected by a lack of jobs," he said, explaining that he saw it outweighing Hindu nationalism as an election issue in the Hindu-majority nation.

Hindu nationalism is a key election theme, especially after Modi's January consecration of a grand temple to the God-king Lord Ram on a site in the northern city of Ayodhya believed to be his birthplace.

Critics accuse Modi's government and party of targeting India's 200 million minority Muslims to please their hardline Hindu base - charges both deny.