Four Indigenous children who went missing in the Colombian Amazon after surviving a plane crash 40 days ago have been found alive, Colombian President Gustavo Petro said on Friday.

The small crash triggered a massive rescue operation for the four siblings.

"A joy for the whole country! The 4 children who were lost 40 days ago in the Colombian jungle were found alive," Petro wrote on Twitter. He posted a photo of military personnel and indigenous people, purportedly involved in the rescue operation.

The rescue operation also included Colombian military airplanes and helicopters.

The military also celebrated the rescue, sharing photos of its personnel apparently with the rescued children.

What do we know about the crash?

The children were rescued near the border between the Colombian provinces of Caqueta and Guaviare, not far from the site of the crash.

The plane was carrying seven people from Araracuara, in the Amazonas province and the Guaviare province's city of San Jose del Guaviare on May 1. An engine failure caused it to crash, killing three adults, including the pilot and the children's mother.

The bodies of all the deceased were found inside the aircraft.

Meanwhile, three children aged 13, 9, and 4 years old and their 11-month-old sibling survived the impact. They are believed to have fled the plane into the rainforest in search of help.

In their search operation, rescuers aided by search dogs found traces of the children's presence, including discarded fruit and improvised shelters made with jungle vegetation.

"They were together, they are weak, let's let the doctors assess them. They found them, it makes me very happy," Petro told journalists on Friday, adding the children had defended themselves alone in the middle of the jungle.

On May 17, Petro had announced finding the children, only to later retract his claim.