According to a close family friend, Kamat suddenly complained of severe chest pain while having his morning tea at his home here.

He called out his driver who rushed him to the Primus Hospital in Chanakyapuri where he is said to have died within minutes.

Kamat is survived by wife Maharookh and son Sunil.

Congress President Rahul Gandhi, former Prime Minister Manmohan Singh and Nationalist Congress Party (NCP) President Sharad Pawar, among other leaders, condoled his death.

UPA Chairperson Sonia Gandhi visited the central Delhi-located hospital where he passed away and placed a wreath on Kamat's body.

Respected across party lines, late Prime Minister Atal Bihari Vajpayee had picked Kamat as part of the four-member official delegation to the United Nations in 2003, along with former Prime Minister I.K. Gujral and former Jammu and Kashmir Chief Minister Farooq Abdullah.

In 2010, Kamat was nominated to represent former Prime Minister Manmohan Singh at the UN International Conference on Federalism in Addis Ababa, Ethiopia.

Kamat, the youthful and secular face of the party and a five-time Lok Sabha member from Mumbai, served as Union Minister of State for Home in 2009 but abruptly resigned in 2011, citing "personal reasons" after his appointment as Minister of State (Independent Charge) for Drinking Water and Sanitation.

He also served as Union Minister of State for Communications and Information Technology.

Kamat had resigned from the Congress in 2016 over his reported unhappiness with the functioning of the local party unit in Mumbai but later withdrew his resignation as the leadership persuaded him against it. He quit all posts last year, though he remained a staunch Congressman till the end.

Considered an able organiser and a good orator, Kamat was President of Mumbai Congress from 2003-2008. He was president of the party's student wing NSUI (1976-80), Indian Youth Congress chief (198-88) and later served the party as a general secretary.

In his last tweet hours before the end, Kamat had extended his greetings on Eid-ul-Azha. On Tuesday, he had greeted party leader Ahmed Patel on his birthday and congratulated him on being appointed party treasurer again.

Rahul Gandhi, who is in Germany, said that Kamat's death is a massive blow to the party.

"The sudden passing away of senior leader Gurudas Kamatji is a massive blow to the Congress family. Gurudasji helped build the Congress in Mumbai and was greatly respected and admired by all. My condolences to his family," he tweeted.

Manmohan Singh said: "I am shocked and saddened to learn about the sudden and untimely demise of Gurudas Kamat. My deepest condolences to all members of his family. I pray to God for the departed soul."

Leader of Congress in Lok Sabha Mallikarjun Kharge wrote to Kamat's son Sunil, expressing his condolences.

"I am extremely saddened to learn about the demise of your beloved father... He was a dedicated public servant and a mass leader of Maharashtra. He will be missed by the country and Congress party in Maharashtra," Kharge said.

NCP chief Sharad Pawar said he is "saddened" as he has "lost a leader who knew the pulse of Mumbaikars and would always voice their concern in Parliament".

Maharashtra Congress President Ashok Chavan said he "lost a great colleague".

State Congress spokesman Sachin Sawant said: "A very dynamic and renowned face of the Congress and a great leader Gurudas Kamat is no more."

Bharatiya Janata Party (BJP) MP from Mumbai North-East Kirit Somaiya expressed shock over his political rival's demise.

"We have lost a gentleman politician, an MP always active for the betterment of Mumbai though we contested Lok Sabha elections against each other," Somaiya tweeted.