Prime Minister Narendra Modi will be sworn in at the weekend after securing a third term in office following an unexpectedly close election that forced his party to rely on coalition partners to keep him in power.

Modi and his ministers will take the oath of office on Sunday, a statement from President Droupadi Murmu's office said on Friday.

Modi's Hindu-nationalist Bharatiya Janata Party (BJP) ruled outright for the past decade but failed to repeat its previous two landslide wins this time around, defying analyst expectations and exit polls.

He was instead forced into quick-fire talks with the 15-member National Democratic Alliance (NDA) coalition, which guaranteed him the parliamentary numbers to govern, although there are no indications yet of any concessions he may have had to offer in return.

Modi presented signed letters of support showing his majority to Murmu, who in turn invited him to form the next government.

"I thank the people that they gave the NDA government a third chance to serve them," Modi said on Friday.

"This is the opportunity and will of the people and I thank them with my heart for this opportunity," he added.

Modi earlier addressed a meeting inside India's parliament of nearly 300 lawmakers forming his coalition and thanked them for unanimously supporting his leadership. The meeting was a formality after the leaders of each party guaranteed their backing this week.

It was also an opportunity to demonstrate the concord between Modi and his new partners in government.

"Modi has a vision and a zeal, and his execution is perfect, and he is executing all his policies with a true spirit," said Chandrababu Naidu, the leader of the premier's largest coalition party ally.

"Today India has the right leader for the right time -– that is, Narendra Modi."

Other party leaders adorned Modi with a garland of purple flowers, while Nitish Kumar, another key supporter, bent to touch the 73-year-old's feet in a traditional gesture of respect.

The alliance will wield 293 seats in the lower house of parliament out of a total of 543.

While it remains unknown what concessions Modi's allies have wrung in return for their support, media reports this week have suggested several are seeking plum ministerial posts.

The Indian Express reported on Friday that Naidu's Telugu Desam Party (TDP) from the southern state of Andhra Pradesh -- which holds 16 seats -- would press for the revival of plans to build a new state legislative capital.

Kumar's Janata Dal (United) party of Bihar state, the BJP's second-largest ally, was seeking a review of a contentious army recruitment scheme introduced by the government in 2022 to cut military expenditure.

Despite the united front, political analyst Zoya Hasan of Jawaharlal Nehru University told AFP that Modi's new coalition alliances could lead to friction down the road.

"Chandrababu Naidu and Nitish Kumar, both are crafty politicians. So, in some ways, Modi might be meeting his match in these two," Hasan said.