He woke up normally this morning but soon after collapsed, possibly due to a heart attack, according to his son A K Dhar.
O N Dhar had worked with Sheikh Abdullah, Bakshi Ghulam Mohammed and Mir Sadiq when they were prime ministers of Jammu and Kashmir till 1965.
Till 1967, the elected head of government in Jammu and Kashmir was called prime minister before the nomenclature was changed to chief minister.