Mumbai: Kim and Khloe Kardashian were spotted in India on Friday, attending a luxurious three-day wedding celebration hosted by Mukesh Ambani, Asia's wealthiest man.

The event will unite Ambani's youngest son, Anant, and his fiancée Radhika Merchant in matrimony over the weekend in Mumbai. Months of extravagant pre-wedding festivities have preceded the main event, setting new standards for opulence in matrimonial ceremonies.

Earlier festivities included a European cruise attended by 1,200 guests, the construction of a Hindu temple at the Ambani family's ancestral residence, and exclusive performances by international stars Rihanna and Justin Bieber.

The Kardashians join a prestigious list of foreign celebrities making appearances at the event. Kim Kardashian shared moments from her arrival on Instagram, where she and her sister were warmly welcomed with flower garlands at their upscale hotel.

Fellow celebrity guests including actor John Cena posed for cameras on the red carpet upon their arrival at the venue, a huge convention centre owned by the Ambani family's conglomerate.

Former British prime ministers Boris Johnson and Tony Blair were also spotted by reporters arriving at Mumbai airport ahead of the party beginning later on Friday.

In June, the couple embarked on a four-day Mediterranean cruise, where singer Katy Perry performed at a masquerade ball at a French chateau in Cannes.

The Backstreet Boys, US rapper Pitbull and Italian tenor Andrea Bocelli also provided entertainment.

Guests at earlier galas have included Facebook founder Mark Zuckerberg and former US president Donald Trump's daughter Ivanka, along with a who's who of India's sporting and entertainment worlds.

This week's opulent celebrations are set to raise the bar further, with even more celebrities, politicians and global business elites jetting into monsoon-hit Mumbai.

Several major roads around the venue have been closed off to the public by authorities for most of the weekend.

Friday will see the main formal ceremony at the 16,000-person capacity venue, with a separate "blessing ceremony" on Saturday and a grand reception on Sunday.

Anant's father Mukesh is chairman of Reliance Industries, a family-founded conglomerate that has grown into India's biggest company by market cap.

The patriarch is the world's 11th richest person with a fortune of more than $123 billion, according to Forbes, and is no stranger to making a statement when it comes to family marriages.

He held the most expensive wedding in India to date for his daughter in 2018, which reportedly cost $100 million and saw US singer Beyonce perform.

Ambani is also a key ally of India's right-wing Hindu nationalist leader, Prime Minister Narendra Modi.

He inherited a thriving industrial enterprise spanning oil, gas and petrochemicals and grew it into a commercial behemoth.

Its lucrative interests include retail partnerships with Armani and other luxury brands, more than 40 percent of India's mobile phone market and an Indian Premier League cricket team.

His 27-floor family home Antilia is one of Mumbai's most prominent landmarks, reportedly costing more than $1 billion to build and with a permanent staff of 600 servants.

Merchant is the daughter of well-known pharmaceutical moguls.