NEW DELHI - Two of the world's richest men, software pioneer Bill Gates and investor Warren Buffett, are set to visit India this week to persuade the country's super-wealthy to part with more of their cash.

Related readings:  Gates: Helping world's poor a good investment  More US billionaires pledge to give away wealth  Microsoft co-founder relaunches tech patent suit  Forbes: Richest people in the world

The pair made headlines last year when they said they would seek to get fellow billionaires to commit half of their wealth to good causes as part of the "Giving Pledge". So far, 59 rich Americans have taken the pledge.

But while charitable giving is widespread in countries such as the United States, it is less well established in developing economies such as India and China, where Gates and Buffett went in September on a similar mission.

The former, in an open letter in the Times of India newspaper, said he and Buffett plan to sit down with some of India's affluent business leaders "to talk about our own enthusiasm for philanthropy and the impact it can have".

"We come not as preachers, but more like cheerleaders," said Gates, just a few months on from the billionaires' high-profile China trip, where they wined and dined the country's richest industrialists to promote charity.

Fast-growing India is home to some of Asia's richest billionaires, making it "an exciting time to be having this conversation," added Gates.

But while there is no shortage of billionaires for Gates and Buffett to meet, it may not be the easiest of missions.

India's booming economy - growing by 9 percent annually - has 55 billionaires with an average net worth of $4.5 billion, according to Forbes, the third-largest pool of billionaires after the United States and China.

Yet rich Indians are often criticized by the local media for their reluctance to part with their cash.

In fact, India's wealthiest social class has the lowest level of giving - just 1.6 percent of household income compared to 1.9 percent for the country's middle classes, according to global consultancy Bain and Company.