The Hercules aircraft went down shortly after departure from Puerto Leguizamo, near the southern border with Ecuador and Peru, strewing burning wreckage on the jungle floor.

The toll was announced in a video statement by regional governor Jhon Gabriel Molina, who said 83 people had been injured.

He added that investigators were probing the cause of the crash.

A military source had earlier intimated that 80 people may have been killed, amid official reports that some 40 survivors had been found.

The troubled border area has been the scene of heavy military activity in recent weeks, as the Colombian and Ecuadoran militaries try to tackle drug-running cartels and militias.

Ecuador's government as well as that of fellow Colombian neighbour Venezuela offered condolences to the families of accident victims.

AFP images from the scene showed civilians clambering around the broken tail of the aircraft, marked FAC 1016, as smoke and flames billowed above the trees.

Defense Minister Pedro Sanchez expressed "deep sorrow" over the disaster as military personnel headed to the remote scene.

"It is a deeply painful event for the country. May our prayers bring some measure of comfort," said Sanchez.

He added it was too early to determine what lay behind the tragedy.

General Carlos Fernando Silva Rueda said that 114 troops were aboard and 11 crew.

They had been travelling between Puerto Leguizamo and another Amazon outpost nearby.

"The airport is small and there are several difficulties" regarding the evacuation of bodies and the injured, Putamayo region governor Molina said in a video posted to Facebook.

Local people recounted they heard a loud bang.

"I felt an explosion in the air and, when I looked up, the plane was flying close to the house on my plot," said Noe Mota, a farmer.

Colombia's left-wing president, Gustavo Petro, shared footage showing the aircraft attempting to gain altitude before plummeting earthwards.

Petro described the crash on X as a "horrific accident" and stressed the need to modernize Colombia's military hardware, without specifically saying if its current state was related to the accident.

The crash is the second by a C-130 Hercules aircraft in South America in under a month.

A Bolivian military cargo plane carrying banknotes crashed while landing near La Paz on February 27, leaving at least 24 people dead.

The Hercules is a four-engine turboprop plane built by Lockheed Martin.

Renowned for its ability to operate from makeshift airstrips, it is widely used by militaries around the world and can carry everything from troops to vehicles.