Russian officials said Navalny died of “natural causes” after he fainted after a walk in the prison colony, nicknamed “Polar Wolf.”
His team condemned the authorities' initial refusal to release his body – they even refused to let his mother see it for several days – accusing them of trying to “cover their tracks”.
G7 leaders also called for truth, praising Navalny's “life of struggle against Kremlin corruption” in a statement on Saturday.
“We call on the Russian government to fully clarify the circumstances surrounding his death,” said the statement from the G7 countries: the United States, Japan, Germany, France, Britain, Italy and Canada.
Thousands of Russians had signed a petition calling for Navalny's body to be released. Dozens of high-profile Russian cultural figures published video messages making the same request.
Earlier on Saturday, Yulia Navalny continued her attack on Putin over his role in her husband's death and his initial refusal to release his body.
“You tortured him alive, now you're torturing him dead,” Yulia Navalnaya said in a video posted Saturday.
He said, “What Putin is doing now is hatred. No, not even hatred, it is a kind of Satanism.”
She has vowed to continue her husband's work.
Navalny died after being held in Russian prisons for three years.
This caused an uproar among the country's opposition and Western leaders, and protests suddenly broke out in cities across Europe.