Less than a month before a grand Hindu temple opens, India's northern town of Ayodhya is buzzing with activity as finishing touches are put on a project seen as the centrepiece of Prime Minister Narendra Modi's re-election campaign.

Once a sleepy temple town in the most populous state of Uttar Pradesh, Ayodhya has received a new airport and roads in a $6-billion facelift as Modi prepares to inaugurate the temple to Lord Ram, one of Hinduism's most revered deities.

A day before Modi was set to inaugurate the airport and a renovated train station, workers decorated the streets with flowers, amid a swarm of police.

"Soon our Lord will be in his original place," said Girish Sahastrabhojane, who worked on the design of the temple, which forms part of a sprawling 70-acre (28-hectare) complex of carved pink sandstone and white marble.

"Our Lord Ram was born here and the Hindus of India, and also abroad, have been waiting for it since 1992," the engineer involved in the construction told visiting reporters.

But Modi's opponents have accused him of stoking religious sentiment to further his political ambitions, and several opposition leaders have declined an invitation to attend the temple's inauguration.

On Jan 22, Modi will pray for the first time before an idol of Lord Ram at the project, which cost more than 20 billion rupees ($240 million), and where more than 4,500 workers are labouring round the clock to complete the ground floor.

Wearing hardhats and safety shoes, they worked on Friday to carve pillars and lift stones amid cranes towering over the site, which Sahastrabhojane said could accommodate 125,000 people in a day.

Modi’s Hindu nationalist Bharatiya Janata Party has long pledged completion of the temple as one of its core aims.

He has made its construction an emotive issue in many speeches ahead of next year’s general elections, widely expected to secure him a third term.

Nationwide riots that killed 2,000 people, most of them minority Muslims, broke out in 1992 after a Hindu mob razed the Babri mosque - where the temple will stand - saying it was built on the site of an earlier Hindu temple.

In 2019, the Supreme Court ordered that Hindus be allowed to build a temple there, ending years of litigation.