Taking to Twitter late Friday night, Petro said: “A joy for the whole country! The 4 children who were lost 40 days ago in the Colombian jungle appeared alive.”
He also attached an image of several members of the military and Indigenous community tending to the siblings — Lesly Jacobombaire Mucutuy (13), Soleiny Jacobombaire Mucutuy (9), Tien Ranoque Mucutuy (4) and Cristin Ranoque Mucutuy (1).
In a separate statement, the President called it a “magical day”, adding: “They were alone, they themselves achieved an example of total survival which will remain in history.
“These children are today the children of peace and the children of Colombia.”
Petro added that he hoped to speak with the children on Saturday.
On May 1, the Cessna 206 light aircraft was flying between Araracuara in Amazonas province and San Jose del Guaviare, a city in Guaviare, when it disappeared.
Since the crash, more than 100 soldiers with sniffer dogs have been deployed in the search and rescue operations.
Last month, the wreckage of the aircraft and bodies of the the pilot and two adults were found.
One of the dead adults, Ranoque Mucutuy, was the mother of the four children.
The family are from the Huitoto people, an indigenous group in south-eastern Colombia and northern Peru.