Kiev: The decades-old Antonov plane that crashed on Wednesday in South Sudan, killing at least 36 people, "was is no state to fly", the Ukraine-based aircraft company said.
"The An-12B was is no state to fly because it failed to undergo timely technical servicing... That should have included work on extending its resources and exploitation timeframe," Antonov said in a statement.
The Antonov firm was spread out across the former Soviet Union plane when the ill-fated plane was built in 1971.
Ukraine was the An-12B's designer. The plane itself was built in Uzbekistan and later registered in the neighbouring Central Asian state of Tajikistan.
It is both a civil and a military transport aircraft that conducted its first test flight in 1957.
The plane crashed just seconds after taking off from South Sudan's capital Juba, smashing into a farming community on an island on the White Nile river.
A spokesman for Antonov in Kiev said the company was now in contact with the aviation authorities of Tajikistan, believing they were responsible for the plane's upkeep.