Paraguayan police have found the remains of seven people in an advanced stage of decomposition a container of fertilizer that arrived in the country from Serbia, officials said Friday.

The remains, discovered by employees of an agricultural company in the capital Asuncion, were likely those of illegal migrants, prosecutor Marcelo Saldivar told reporters.

Local shipping authorities said the container had left Serbia in July, first for neighbouring EU member Croatia -- the migrants' likely destination -- before travelling through Egypt, Spain and Argentina en route to Paraguay.

Traces of food discovered near the remains suggested the group was "prepared for a short trip," Saldivar told reporters.

Asphyxiation was the likely cause of death, forensic doctor Pablo Lemir said, adding that three of the seven were from Morocco and one was from Egypt.

The remains appeared to be adult and male, he said, adding that the fertilizer could have sped up the process of decomposition.

Personal items discovered on the bodies included a telephone card in the cyrillic script used in Serbia. 

Saldivar said Paraguayan authorities would seek contact with authorities in Serbia through Interpol to trace the remains.