Admitted to the AIIMS some days ago with chest pain and neuro problems, Singh complained of breathing problem around 1730 hours. He suffered a heart attack and breathed his last around 1815 hours, sources said.
A loyalist of the Gandhi family, Singh was vice president of the Congress under Rajiv Gandhi in the eighties and was also Governor of Punjab at the height of militancy and was instrumental in the Rajiv-Longowal accord.
Incidentally, Singh was today dropped from the party's highest policy making body Congress Working Committeee on Friday and was made a permanent invitee.
Singh leaves wife Saroj Devi, two sons--Ajay Singh, an MLA in Madhya Pradesh and Abhimanyu--and daughter Veena.
Singh was a close adviser to Sonia Gandhi when she decided to enter politics and became the Congress president in 1998. He was said to have been behind her unsuccessful attempt to become the prime minister after the fall of the Vajpayee government in April 1999.
Gandhi then staked her claim to form the government on the basis of support of 272 MPs but ultimately she did not have the numbers. But the political wheel turned a full circle when he lost his proximity to Sonia Gandhi and that could have played a part in not being able to realise his prime ministerial ambitions.
However, as human resource development minister in the first United Progressive Alliance government from 2004, Singh was instrumental in championing the cause of backward classes and piloted bills for ensuring reservation for them in institutions of excellence.
With failing health, Singh, who started using a wheel chair in the last years, did not make it to the Union cabinet when Dr Manmohan Singh took oath as the prime minister for a second time.
But his strong loyalty to the Gandhi family came into prominence when he made a rare appearance in the Rajya Sabha last year to apportion blame on the late Narasimha Rao to say that Union Carbide chief Warren Anderson was allowed to go out of the country under the instructions from the home ministry then headed by Rao.
Image: Congress leader Arjun Singh | Photograph:
Kamal Kishore/Reuters