India has been shamed by a string of high-profile rapes and sexual attacks on women, the country's prime minister, Narendra Modi, has said in his first Independence Day speech as prime minister.

Addressing the nation from the Red Fort citadel in Delhi, Modi called on Indian parents to take responsibility for the actions of their sons, rather than put the blame on their daughters. He said every Indian household should have a toilet within the next four years, and promised separate toilet facilities for girls in public schools.

"Our heads hang in shame when we hear about rapes," he said. "Why can't we prevent this? When a daughter steps out, parents demand to know where she's going. But when a son returns home, does anyone dare ask where he is coming from? He might have been with the wrong people, doing wrong things. After all, a person raping is someone's son. Why don't parents apply the same yardstick of good behaviour for their sons as for their daughters?"

A brutal gang rape on a moving Delhi bus in December 2012 has led to an unprecedented national debate about sexual violence and prompted calls for changes in cultural attitudes as well as policing and legal reform. But many attacks still go unreported amid an entrenched culture of tolerance for sexual violence and social stigma for the victims of such assaults.

"The law will take its own course, but as a society every parent has a responsibility to teach their sons the difference between right and wrong," the prime minister said.

Modi's tone throughout his hour-long speech in Hindi was part beseeching, part admonishing, as he took up issues ranging from eradicating poverty and ending Maoist violence to reforming bureaucracy and ending Soviet-style central economic planning.

But he got the maximum applause when he spoke on gender-related issues. "Look at our sex ratio – 1,000 men to 940 women," he said. "Who is creating this imbalance in society? Not the Almighty. I appeal to doctors not to kill the girl child."

Modi called on politicians to ensure more toilets were built for girls and women. "Can't we just make arrangements for toilets for the dignity of our mothers and sisters?" he said.

In May two teenage girls were found hanged from a tree after being gang-raped while going to the toilet in the fields because – like around half of the country's population – there was no toilet at home.

"We are in the 21st century and yet there is still no dignity for women as they have to go out in the open to defecate and they have to wait for darkness to fall. Can you imagine the number of problems they have to face because of this?" Modi said.

Unlike his predecessors, Modi did not read out a tedious list of achievements and promises from a prepared text, but addressed the people directly. And he dispensed with the bullet-proof screen on the podium. The nationally telecast speech was trending immediately on Twitter.

He portrayed himself as an outsider, "an untouchable to the elite class of Delhi", who was battling with vested interests to bring about change. He described himself as "not a prime minister but a prime sevak [one who serves]".

Mahatma Gandhi's grandson, Tushar Gandhi, said: "The tone of the speech was very grand, but the words were very humble."

In the midst of homilies about national character, Modi also made a couple of significant policy statements.

He announced a government scheme to help poor people open savings accounts, which would come with a debit card and a 100,000 rupee (£985) health insurance policy.

About 40% of Indian households do not have bank accounts. If the functioning of anti-poverty programmes that are prone to massive corruption is to improve, direct cash transfers to poor people is now being touted as a solution. For this to succeed, there has to be a major expansion in retail banking.

In a clear signal that the era of a centralised, Soviet-style command economy was over, Modi announced the scrapping of the planning commission, set up in 1950 to formulate five-year plans for investment and development in all states. It will be replaced by a new "development and reform" body in which provinces will have a greater say.

Modi was criticised by the opposition for his almost cursory reference to the inter-religious violence in the last three months, after his Hindu nationalist party came to power. He appealed to the people to shun communal violence and work instead for the nation's progress.

Modi ended his address with slogans dear to Hindu nationalists. Besides the customary "Jai Hind!" (Hail India!), he added two more slogans hailing "Mother India".