"The nation has lost a tall leader and the North-East has lost an important voice," the Congress President Sonia Gandhi said in a message.
Sangma along with NCP chief Sharad Pawar and Tariq Anwar had parted ways with Congress in 1999 on the issue of Sonia Gandhi's foreign origin.
Gandhi recalled the contribution of Sangma as a public representative, Union Minister, Chief Minister and Speaker of the Lok Sabha.
Leader of the opposition in the Rajya Sabha Ghulam Nabi Azad said it is "very saddening" to hear about the sudden demise of Sangma.
Congress General Secretary Digvijay Singh expressed grief over the death of Sangma whom he hailed as a "most affable and likeable person."
Pawar also took to micro-blogging site to express grief over the death.
"PA Sangma vibrant, dedicated parliamentarian & effective speaker. My close companion! Heartfelt tribute to him. Champion of northeast issues," Pawar said.
