Hundreds of people set out from Mumbai to India's capital, New Delhi, on Thursday in a caravan aimed at pressuring authorities to speed up trials of perpetrators of sex crimes, and to encourage victims to speak out.

Government data shows reported cases of overall crimes against women rose by 83 percent from 2007 to 2016, a year when four rape cases were reported every hour.

Campaigners say many sexual attacks remain unreported, as victims fear stigma or retribution.