The body, which was wrapped in plastic, was discovered by workers around 130 centimetres below the surface at the Norra cemetery in Solna, north of Stockholm.
“We were in the process of digging a grave. When we got down a bit, we came across a corpse that was partly wrapped in plastic,” Lars Wetterlund, head of the cemetery, told the TT news agency.
Wetterlund added that the body looked as if it had been buried recently, and that the plastic wrapping made it impossible to determine the sex or age of the child.
“But it’s not an infant, that much I can say,” he said.
Police suspect that the child had been murdered, a source told the Aftonbladet newspaper.
It was only by chance that the diggers found the body, as they were excavating a section of the burial grounds that was supposed to be unused.
“It was disturbing. Sometimes we find old bone remains, but in this case it felt like something was truly wrong,” Wetterlund added.
A forensics team has cordoned off the area and police have launched an investigation. Work is expected to carry on through the night.