Modi launched as many as 81 investment projects worth over Rs 60,000 crore in the capital city of Uttar Pradesh.
The prime minister on Sunday said he was not afraid of being seen with industrialists playing a key role in the nation's development, as he slammed the opposition parties for the "mistakes" made during 70 years after India's independence.
"You cannot have blot on you simply by standing with anyone if your intentions are good and clear. Gandhiji's intentions were so pure that he never hesitated in staying with Birla family," he said.
"Public mey milna nahi, parde ke peeche sab kuch karna hai. Woh dartey rahtey hain. (Those who do not meet publicly and do everything behind curtains remain scared)," he said.
Amar Singh, former SP leader, is sitting here and he can give you all the details, Modi said with a laughter.
Singh was also seen at the inauguration and flagging-off of electric buses by Uttar Pradesh Chief Minister Yogi Adityanath at his official residence later in the day.
On July 23, Singh had met Adityanath, triggering speculation in political circles that he might be planning to join the BJP.
Though the meeting was confirmed by official sources, it was not immediately known what transpired between them.
Rumour is rife that Singh, who was a Rajya Sabha MP from the Samajwadi Party but was expelled from the outfit last year, has been toying with the idea of embracing the saffron party.
Singh had recently said that he was not averse to joining the BJP, but he had not got any invite from it, nor had he applied to it.
"The BJP is a very big political party. I won't say that I will not join the BJP if I get a chance, but who is giving me the chance? I have not sent them any request letter either," he said.