The attack, which came amid a major Indian offensive aimed at crushing the Maoists, fueled concerns the government is sending poorly trained forces to the front lines to battle the raging insurgency.
Indian Home Minister Palaniappan Chidambaram, the nation's top law enforcement official, said the attacks showed "the brutality and the savagery" of the rebels.
At least 82 troops were in a patrol party that had spent three or four days scouring forests in the rebel stronghold of Dantewada, in Chhattisgarh state, said R.K. Vij, the inspector general of state police.
Early Tuesday, rebels ambushed some of the troops, killing at least three of them, he said. Another 17 troops who went to recover the bodies were killed when their vehicle was blown up by a land mine, Vij said - although the vehicle was designed to withstand such explosives. More troops died as the fighting continued to rage throughout the afternoon, he said.
The bodies of 75 paramilitary troops were recovered by Tuesday afternoon in the remote and heavily forested area, he said.
Seven troops were also wounded, three of them critically, he said. The government found no rebel bodies, Vij said.
Few other details are available from the area. The rebels rarely speak to the press, aside from issuing occasional statements.
The rebels are known as Naxals or Naxalites, after Naxalbari, the village in West Bengal state where their movement was born in 1967. In February, they killed at least 24 police officers in West Bengal in a stunning attack on their camp.
Inspired by Chinese revolutionary leader Mao Zedong, the rebels have tapped into the rural poor's growing anger at being left out of the country's economic gains and are now present in 20 of the country's 28 states. They have an estimated 10,000 to 20,000 fighters.
The troops were part of the government's "Operation Green Hunt" offensive aimed at flushing the militants out of their forest hide-outs.
Several experts said the government offensive was flawed and the inadequately trained and poorly equipped soldiers were often sitting ducks for Maoists much more familiar with the terrain.
"It's a flawed operation," said K.P.S. Gill, a retired senior police officer who has been involved in several operations in insurgency-hit areas.
"What is the point of a four-day patrol? You have a fatigued force in the heat of Chhattisgarh at this time of the year," he said.
April temperatures in the area often hit 110 degrees Fahrenheit (43 degrees Celsius).
He also called the anti-mine vehicles used by the troops "death traps."
"More men are lost in an anti-mine vehicle than outside it," he said.
In the past few months that the Indian government has cracked down on the rebels it has also said it was ready to discuss all their demands, but only if they gave up violence.
About 2,000 people - including police, militants and civilians - have been killed in violence over the past few years.
