Image copyright Getty Images Image caption Millions of poor Indians still defecate in the open

Two men in the central Indian state of Madhya Pradesh have been arrested for allegedly killing two Dalit (formerly untouchables) children who were defecating in the open, police say.

Roshni, 12, and Avinash, 10, were attacked on Wednesday while defecating near a village road, they said.

The children's family told BBC Hindi that they have no toilet at home.

Millions of poor Indians defecate in the open, which especially puts women and children at risk.

Dalits are at the bottom of the Hindu caste system and despite laws to protect them, they still face widespread discrimination in India.

"The two children were beaten to death with sticks," police superintendent Rajesh Chandel told BBC Hindi's Shuraih Niazi. "We have registered a murder case against both the accused. They are being questioned."

Within hours of the attack early on Wednesday morning, police arrested two upper-caste men - Rameshwar Yadav and Hakim Yadav.

Roshni and Avinash were cousins, but Roshni had been brought up by Avinash's parents and lived with them.

Avinash's father, Manoj, says that as a daily wage labourer, he cannot afford to build a toilet at his house. He also says he has been unable to access a government subsidy as part of a flagship scheme to build toilets for the poor.

Video caption Newsnight: Unblocking India's sewers... by hand

The Swachh Bharat Mission or Clean India programme seeks to end open defecation by increasing toilet infrastructure and improving sanitation across the country. When Prime Minister Narendra Modi launched the program in 2014, he vowed to make India "open defecation free" by 2 October 2019.

Manoj's village - Bhavkhedi - has been declared "open defecation free", a tag given by the government to villages and cities have successfully ended open defecation.

Image caption Women who go out at night to defecate are often at risk

Research has shown that while the construction of toilets has increased rapidly, lack of water, poor maintenance and slow change in behaviour have stood in the way of ending open defecation.

But many have praised Mr Modi for highlighting the issue and launching a major scheme to address it - the Bill & Melinda Gates Foundation honoured him this week, describing the Swachh Bharat Mission as "a model for other countries around the world that urgently need to improve access to sanitation for the world's poorest."