A trio of Americans on Monday won the Nobel Economics Prize for their work in the fight against poverty, including Esther Duflo, the youngest-ever economics laureate and only the second woman to win the prize.

Duflo -- a 46-year-old French-American professor who has served as an advisor to ex-US president Barack Obama -- shared the Nobel with her husband, Indian-born Abhijit Banerjee and fellow American Michael Kremer "for their experimental approach to alleviating global poverty," the Royal Swedish Academy of Sciences said.

"This year's laureates have introduced a new approach to obtaining reliable answers about the best ways to fight global poverty," the jury said.

'A new approach' in the fight against global poverty / © AFP

The science academy said that "more than 700 million people still subsist on extremely low incomes", and that around five million children under the age of five still die every year from preventable or curable diseases.

The trio found efficient ways of combating poverty by breaking down difficult issues into smaller, more manageable questions, which can then be answered through field experiments, the jury said.

Duflo is only the second woman to win the Nobel Economics Prize in its 50-year existence, following American Elinor Ostrom in 2009.

- Ultra rich, ultra poor -

Banerjee and Duflo are professors at the Massachusetts Institute of Technology (MIT), while Kremer is a professor at Harvard University, all based in Boston.

Duflo has made her name conducting research, together with her husband, who was her PhD supervisor, on poor communities in India and Africa, seeking to weigh the impact of policies such as incentivising teachers to show up for work or measures to empower women.

Her tests, which have been likened to clinical trials for drugs, seek to identify and demonstrate which investments are worth making and have the biggest impact on the lives of the most deprived.

"Economics have a lot to say why the times are hard and what to do about it," Duflo said at a press conference at MIT in Boston.

"The two groups that did relatively well in the world economy are the ultra-rich and the ultra-poor."

But she noted that even when basic material comforts are covered for people in developed economies "their full life might have the same level of misery and unhappiness that some of the extremely poor people we study."

Banerjee said governments have not taken seriously the harm inflicted from globalisation.

"The policy response to the pain caused by globalisation was inadequate often been the wrong direction," he said.

- Not enough women -

Duflo told the Nobel committee in a phone interview that she didn't think it was possible to win the prize "before being significantly older than any of the three of us."

Banerjee is 58 and Kremer is 54.

Addressing the fact that so few female economists have been honoured, Duflo said this was also a reflection of the field in general.

"There are not enough women in the economics profession period, so you see this problem at all levels," Duflo told the Nobel Prize website.

'Our vision of poverty is dominated by caricatures and cliches' / © AFP

In the past 20 years, more than three-quarters of economics laureates have been American white males over the age of 55.

French President Emmanuel Macron hailed the "magnificent" Nobel awarded to Duflo, writing on Twitter that her work "shows that research in this field can have a concrete impact on the well-being of humanity".

Duflo said her husband and fellow laureate had "gone back to sleep" after receiving the call from the academy.

Indian-born Abhijit Banerjee is a vocal critic of Prime Minister Narendra Modi / © AFP

Banerjee in a later interview confessed he was not "an early morning person".

But he said he was "delighted" that research into alleviating poverty had received some attention.

The son of two economists, Banerjee grew up in Kolkata in eastern India, and has been a vocal critic of Indian Prime Minister Narendra Modi.

Ahead of elections earlier this year -- that saw Modi cruise to a second term -- Banerjee advised the opposition Congress party on its proposed guaranteed basic income guarantee scheme for tens of millions of India's poorest.

In the 1990s, Kremer used field experiments to test interventions to improve school results in western Kenya.

He has also helped develop programmes to incentivise the distribution of vaccines for diseases in the developing world.

- Only Nobel not in will -

Unlike the other Nobels awarded since 1901, the Economics Prize was not created by the prizes' founder, philanthropist and dynamite inventor Alfred Nobel, in his 1895 will. It was created in 1968 to mark the 300th anniversary of Sweden's central bank, and first awarded in 1969.

Kremer worked in schools in Kenya and helped with vaccines programmes / © Harvard University/AFP

Each of the Nobels comes with a prize sum of nine million Swedish kronor ($914,000, 833,000 euros), to be shared if there is more than one winner in the discipline.

But unluckily for recent winners, the prize's value has lost around $185,000 in the past two years, due to the depreciation of the Swedish krona.

This year's Nobel laureates will receive their awards at ceremonies in Stockholm and Oslo on December 10, the anniversary of the 1896 death of Alfred Nobel.