A Swedish-backed resolution circulating at the United Nations General Assembly on Wednesday seeks to relaunch an investigation into the death of the world body's late chief Dag Hammarskjold, who was killed in a 1961 plane crash in Africa.
The text, a copy of which AFP obtained, calls on all 193 member states to produce all "relevant documents" and other information on the Swedish diplomat's death in what is now Zambia.
That puts extra pressure on Belgium, Britain, France, Russia, South Africa and the United States, which are believed to still hold secret archives that have not yet been shared.
The draft text also calls for promptly appointing an "independent and high-ranking official to conduct a dedicated internal review of their intelligence, security and defence archives," and for the UN chief to work toward centralizing all information relevant to the probe.
A vote is expected by the end of the month.
Hammarskjold had been traveling in an Albertina DC6 near the city of Ndola in Northern Rhodesia -- now Zambia -- when it crashed. Fifteen other people died in the crash.
At the time, the Swedish diplomat was seeking to unite Congo and stop the mineral-rich Katanga province from seceding.
Two investigations concluded the crash was caused by pilot error. But since 2015, new probes have focused on a possible plot.
The French Foreign Ministry said its archives on the matter were "accessible."
"France hopes that everything behind this tragedy can be brought to light," it said.
Hammarskjold's death happened "a long time ago, but it's important for the relatives of the victims and for the UN as an organization... to have the truth about this," Swedish Foreign Minister Margot Wallstrom said in October.
"There could be secrets in all of this... things that countries will not want to reveal."