India has 121 billionaires -- 19 more than last year -- making them the third largest group of the ultra-rich after those from the US and China, according to Forbes, the business magazine that produces an annual list.

Mukesh Ambani, the energy and petrochemicals magnate, who keeps his standing as the richest Indian, is richer by $16.9 billion in 2018 with assets of $40.1 billion, according to the magazine's list released online on Tuesday.

He moved up to the 19th global rank on the list of 2,208 billionaires worldwide compiled by Forbes. In 2017, he ranked 33rd with $23.2 billion.

The US has 585 billionaires and China 373 this year on the Forbes tally, which it calls "The Three Comma Club" for the punctuation used in writing out fully the billion in numbers.

In 2017, there were 102 Indians on the list.

Amazon founder Jeff Bezos is the world's richest man with assets valued at $112 billion, overtaking Microsoft co-founder Bill Gates whose fortunes are valued at $90 billion and investor Warren Buffet with $84 billion.

In 2017, Gates ranked first globally with $86 billion, Buffet second with $75.6 billion and Bezos third with $72.8 billion.

Bezos, who also owns The Washington Post newspaper, is the first person to cross the $100 billion mark in assets, Forbes said. His fortunes rose by $39.2 billion over the past year, which Forbes said is the list's biggest one-year jump ever.

Gates, who heads the world's biggest philanthropic organisation, the Bill and Melinda Gates Foundation, has donated a lot of his assets to charities.

The software entrepreneur Azim Premji moves to the second richest Indian spot in 2018, passing Lakshmi Mittal, the international steel tycoon, according to the magazine.

Premji moved up from the 72nd global spot in 2017 with $14.9 billion, to the 58th rank with $18.8 billion this year.

Although the value of his assets have increased over the past year, Lakshmi Mittal slid to the 62nd rank on the 2018 global list and to the third spot among Indians with $18.5 billion from the 56th worldwide rank with $16.4 billion in 2017.

The richest Indian woman on the Forbes list is Savitri Jindal of the Jindal steel and power conglomerate, who ranks 176th globally on the Forbes list with $8.8 billion.

Next is the biotech entrepreneur Kiran Mazumdar-Shaw at 629 with $3.6 billion.

The 39-year-old financial technology entrepreneur Vijay Shekhar Sharma, who ranks 1,394th globally with $1.7 billion, is the youngest Indian on the Forbes list.

Software company HCL's founder Shiv Nadar is the fourth richest Indian on the list with $14.6 billion and is ranked 98 globally.

Sun Pharmaceuticals founder Dilip Shanghvi ranks next as the fifth riches Indian with $12.8 billion at the 115th global spot.

The Indian pharmaceutical sector has the most number of billionaires - 16.

It is followed by consumer goods with 15 billionaires, real estate with nine, and software services and diversified investments with eight each.

Nirav Modi, the jeweller who has reportedly been linked to an alleged $2 billion-fraud involving the Punjab National Bank, was not on last year's or this year's global list of billionaires, but a separate list of only Indian billionaires published by Forbes in October ranked him 85th with assets worth $1.8 billion.

Many people of the Indian diaspora also figure on the Forbes list. Construction magnate Pallonji Mistry, who is listed as Irish, is ranked 66th with $17.8 billion.

There are nine others of Indian origin with assets over $2 billion from Australia, Britain, Malaysia, Indonesia, Singapore and the US.

The top Indian billionaires

Here is a list of the richest Indians on the Forbes list with assets over $8 billion. (Their global rank is shown before their names and the sector and value of assets as listed by Forbes follow their names.)

19 Mukesh Ambani ($40.1 billion, petrochemicals, oil & gas)

58 Azim Premji ($18.8 billion , software services)

62 Lakshmi Mittal ($18.5 billion, steel)

98 Shiv Nadar ($14.6 billion, software services)

115 Dilip Shanghvi ($12.8 billion, pharmaceuticals)

127 Kumar Birla ($11.8 billion, commodities)

143 Uday Kotak ($10.7 billion, banking)

151 Radhakishan Damani ($10 billion, investments, retail)

154 Gautam Adani ($9.7 billion, commodities, ports)

170 Cyrus Poonawalla ($9.1 billion, vaccines)

176 Savitri Jindal ($8.8 billion, steel)

176 Sunil Mittal ($8.8 billion, telecom)