NEW DELHI: India is home to the world's largest number of stunted children due to a lack of toilets, dirty water and poor hygiene, according to a new study published on Tuesday.

Despite high economic growth in recent years, India has more stunted children than Nigeria, Pakistan, China and the Republic of Congo combined, with 48 million under the age of five -- about 30 per cent of the global total, a WaterAid report said.

Stunting is a form of malnutrition in which children are shorter than normal for their age and is largely irreversible after the age of two.

If they survive, they grow up physically and intellectually weaker than their better-fed peers.

WaterAid says a lack of toilets and clean water are causing high levels of stunting in India. That is because high rates of open defecation lead to contamination that can spread disease and infection.

Data collated by WaterAid showed that 140,000 children die every year from diarrhoea in India, while 76 million do not have access to safe water and 774 million live without adequate sanitation.

“India has the highest number of people in the world... practising open defecation, which spreads deadly diseases and makes children more susceptible to diarrhoea and other infections,” said Megan Wilson-Jones, WaterAid health and hygiene analyst.

“So it is no surprise that so many children in India suffer from stunted growth,” she added.

Open defecation has long been a major health and sanitation problem in India, where almost 594 million people -- nearly half the population -- defecate in the open, according to UNICEF.

Prime Minister Narendra Modi has stressed the need to clean up India since storming to power in 2014 and has repeatedly urged every household to have a toilet within four years to end the spread of disease.

Nigeria ranked second with 10.3 million stunted children while Pakistan stood third in WaterAid's study with 9.9 million.

Impoverished Bangladesh fared better than its bigger, wealthier neighbour India, recording 5.5 million cases in its 160 million-strong population.

The country has almost eliminated open defecation in just over a decade through a concerted campaign to build toilets.

East Timor was the country where stunting was most prevalent. Nearly 58pc of the young nation's children suffered from the condition, while Germany had the lowest rate at 1.3pc.