He said the efforts to bring back black money stashed abroad are on the "right track" even as he acknowledged that there was no correct estimate about how much money is kept illegally in foreign countries.
In an address to the nation over radio, he said that bringing back black money from outside the country is an "article of faith" for him and nothing will be lacking in his efforts to do so.
The Prime Minister's commitment to bring back black money stashed abroad comes against the backdrop of the stand it first took in the Supreme Court last week about the inability to disclose the names of the account holders in foreign banks because of the confidentially clause in treaties with other countries.
It had maintained that disclosure of details of account holders would hamper efforts to bring back black money.
The government beat a hasty retreat after the Supreme Court ordered it to disclose the names of account holders in HSBC Geneva which amounted to 627 in number. The government also came under attack from opposition parties that it was going back on its election promise to unearth and bring back black money stashed abroad.
Modi said there may be differences in approach on getting this money back but he was committed to doing it and the nation should have faith in him.
"As far as black money is concerned. You should have faith on this 'pradhan sevak'. For me, it is an article of faith. Every penny of the money of poor people in this country, which has gone out, should return. This is my commitment," Modi said in Mann ki Baat programme on All India Radio.
"There may be differences over the approach and procedures, which is natural in a democracy. But as far as my understanding goes and on the basis of information I have, I can say we are on the right track," he said.
On the actual estimate about amount in illegal bank accounts in foreign countries, the Prime Minister said, "Nobody knows, nor do I know, nor does the government know, nor do you know, how much money is stashed abroad.Even the previous government had no estimate.
"Everybody is making own assessment of figures. I do not want to get involved in those figures. It is my commitment that whatever amount, Rs 2, Rs 5, crore of rupees or whatever, this money belongs to the poor people of this country and should come back.
"And I can assure you that nothing will be lacking in my efforts. I only want your blessings to continue."
He asserted that whatever has to be done, will be done at the earliest.
In his second radio address, which lasted about 20 minutes, the Prime Minister also talked about his government's initiatives like those related to the specially-abled children and cleaning the country besides social problems like drug addiction.
He also paid tributes to the armed forces while referring to his visit to Siachen in Jammu and Kashmir on Diwali day on October 23 where soldiers live in difficult conditions.
With regard to the specially-abled people, he announced that a special scholarship will be given to 1000 such children by the HRD Ministry.
Rs one lakh each will also be given to Kendriya Vidhyalayas and central universities for creating infrastructure for the specially-abled children, he said.
"A good beginning has been made and things will change," he said and added that the country is headed towards a "big change".
Talking about the 'Swachh Bharat' drive launched on October 2, he appreciated the personalities from various walks of life as well as common people for participating in the campaign.
"Had anybody thought that it will become a nationwide campaign... Things are changing and people are becoming aware that they should not throw filth around," Modi said, adding the maximum impact of the drive has been on children.
Linking the cleanliness drive to healthcare, he said the poor people are the worst affected by dirt as they fall ill which affects their livelihood.
While talking about the changing mindset of people on the issue, he said that many personalities, including business leaders, sports persons and film actors who meet him now discuss social issues.
"Earlier, when business leaders used to meet (the Prime Minister), they would discuss issues of their interest. But now, most of the discussions centre around social issues," the Prime Minister noted.
Modi talked about the problem of drug addiction, citing a letter received from a citizen in this regard. He invited suggestions from public on how best to deal with this social problem and promised to speak on it during the next Mann Ki Baat programme.
He said youth are the asset of the country and the nation cannot afford to see them falling into the problem of drug abuse.
"The issues I touch are the ones on which government comes under attack. But how long will be hide things For good intent, the truth has to be spoken and I will keep doing it," he said.
He said the government has a responsibility to address social problems like drug addiction and it will create an environment in this regard.
The Prime Minister recalled that during his first address on AIR he had advocated people to buy at least one khadi product. He said he checked the impact of his appeal later and found that sale of khadi products at Khadi Bhandaar had gone up by 125 per cent during one week around Gandhi Jayanti as compared to the same time last year.
"Some think people are useless and should not engage them. This is wrong. There is a need to change that mindset. People are much ahead while governments are lagging," he said.
He said he particularly finds youngsters full of energy and aspiration to do something.
He invited public to share their views and suggestions to him either directly through social media or address it to Mann Ki Baat programme.