Kremlin officials rejected on Tuesday a call for an independent postmortem examination on the remains of opposition leader Alexei Navalny.
The Council of the European Union had on Monday called for the independent review, saying Russia "must allow an independent and transparent international investigation into circumstances of his sudden death."
"Mr Navalny's unexpected and shocking death is yet another sign of the accelerating and systematic repression in Russia," the council said in a statement.
A spokesperson for Russian President Vladimir Putin rejected the body's request on Tuesday, saying, "Moscow does not accept such demands" from the European Union.
Navalny, a long-time Russian opposition politician and critic of the Kremlin under Putin, died in prison at age 47 on Friday, the state prison service said.
MORE: Navalny's widow vows to continue husband's opposition to PutinMembers of Navalny's inner circle said they were continuing on Tuesday to seek access to the opposition leader's remains.
Yulia Navalnaya, Navalny's widow, on Tuesday called for the remains to be returned so they could be "buried with dignity."
Navalnaya had vowed on Monday to continue his opposition against Putin. She released a video in which she alleged that Navalny's body was being kept from the family because he had been murdered, perhaps by poison.
Dmitry Peskov, the Kremlin spokesperson, on Tuesday said those allegations were "unfounded, unsupported and borish."
"I don't care how the killer's press secretary comments on my word," Navalnaya said in a response posted on X, after which her account was briefly inaccessible.
Navalny's mother, Lyudmila, addressed Putin directly in a separate video. She's been in the Arctic for five days trying to access her son's body.
MORE: Alexei Navalny's allies accuse Russian authorities of deliberately withholding his body"Let me finally see my son," she said while standing in front of the Arctic prison camp where Russian officials said Navalny died. "I demand the immediate handing over of Alexey's body, so that I can give him a humane burial."
Meanwhile, the White House is set to announce a new "major sanctions" package on Friday "to hold Russia accountable" in response to Alexei Navalny's death.
"Whatever story the Russian government decides to tell the world, it's clear that President Putin and his government are responsible for Mr. Navalny's death," National Security Council Coordinator John Kirby said Tuesday morning.
ABC News' Joe Simonetti and Patrick Reevell contributed to this story.