New Delhi (AFP) - India's 100 richest people are for the first time all billionaires, according to an annual Forbes survey released Thursday, nearly double the number from five years ago.

The country's top earners were also worth a third more combined than last year as Indian stock markets went on a roll with the election of the new right-wing government led by Prime Minister Narendra Modi.

Industrialist Mukesh Ambani topped the list for an eighth straight year with his $23.6-billion fortune, Forbes India said on its website. The wealth of Ambani, chairman of conglomerate Reliance Industries, climbed by $2.6 billion from last year.

The combined worth of the 100 richest Indians now totals $346 billion, Forbes said, an increase of a third on 2013 fuelled by stock prices up nearly 30 percent since January.

The figures come amid disquiet in India about a yawning divide between the elite and burgeoning middle classes and hundreds of millions still living in deep poverty.

While India's mega-rich host multi-million-dollar weddings for their children, host lavish parties, fly private jets and have armies of servants, the poor often toil in the shadows of mansions and office skyscrapers, scavenging and living in disease-infested slums with no sanitation.

The minimum sum to qualify for the Forbes list was $1 billion for the first time, up from $635 billion in 2013.

India's 100 billionaires this year is nearly double the 52 in recorded in 2009 but the number is still lower than rival emerging market giant China's 152 billionaires, according to a Forbes list released in March.

Indian pharmaceutical magnate Dilip Shanghvi, whose wealth grew by $4.1 billion to $18 billion, is the new number two on the list, displacing London-based steel baron Lakshmi Mittal. The Indian-born magnate slipped to fifth place at $15.8 billion.

Shanghvi's wealth surged after his Sun Pharmaceuticals bought rival generic giant Ranbaxy Laboratories from Japan's Daiichi Sankyo for $4 billion in April, Forbes said.

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The pharmaceutical sector is one of India's biggest wealth generators, with over a fifth of the 100 richest holding assets in the drugs and health care sectors, Forbes said.

Moving up to third place was Azim Premji, chief of outsourcing giant Wipro, whose fortune climbed by $4.1 billion to $18 billion.

- 'Gloom to boom' -

The rise in India's share prices has vastly outpaced economy expansion running at under six percent, well below near double-digit levels of a few years ago.

India's mood has "moved very quickly from gloom to boom" under the new government which took office in May, said Naazneen Karmali, India editor of Forbes Asia.

"The new federal government's mandate for change has sparked euphoria in the stock market, causing a seismic shift in Indian wealth this year," Karmali added.

Tycoon Vijay Mallya, known as the "King of Good Times", fell off India's most wealthy list, engulfed by massive debts of his grounded carrier Kingfisher Airlines, named after his beer brand.

The flamboyant Mallya has been declared a "wilful defaulter" by creditors -- someone who is able but unwilling to pay. Mallya, who owes over $1 billion to a consortium of state-run banks, is chairman of United Spirits, controlled by global liquor giant Diageo.

Mallya was in 84th spot with $800 million on the wealth-tracking list last year.

The Indian businessman who made the biggest jump was ports magnate Gautam Adani, who hails from Gujarat, the same state as Modi, and who is seen as close to the Indian leader.

Adani leapt 11 spots in the wealth stakes to number 11 as shares of his companies climbed around election time.

India's richest are still significantly worse off than the world's wealthiest man, Microsoft co-founder Bill Gates, who is worth an estimated $76 billion.