Rajya Sabha MP and former Samajwadi Party leader Amar Singh, 64, passed away on Saturday.
He was undergoing treatment at a hospital in Singapore for several months.
Several leaders paid tributes to Singh.
Union minister Nitin Gadkari said in a tweet that he felt very sad to hear the news of the demise of Amar Singh. "May his soul rest in peace," he said.
DD news tweeted: "Rajya Sabha MP Amar Singh passes away; he was undergoing treatment at a hospital in Singapore for several months."
BJP leader Shahnawaz Hussain also paid his tributes. "Sad at demise of Amar Singh. He was friend of friends," Hussain said in a tweet.
( With inputs from ANI )