Washington CNN  — 

After days of near silence from the Trump administration, Secretary of State Mike Pompeo on Tuesday released a statement expressing concern about preliminary medical reports that a prominent Russian opposition leader was poisoned and supporting an investigation “if the reports prove accurate.”

“The United States is deeply concerned by reported preliminary conclusions from German medical experts that Russian opposition activist Aleksey Navalny was poisoned,” Pompeo said. “If the reports prove accurate, the United States supports the EU’s call for a comprehensive investigation and stands ready to assist in that effort.”

“Mr. Navalny’s family and the Russian people deserve to see a full and transparent investigation carried out, and for those involved to be held accountable,” he said. “Our thoughts are with Mr. Navalny’s family and we hope for his full recovery.”

Pompeo’s statement comes nearly a week after Navalny’s spokesperson announced that the Kremlin critic was in a coma after falling ill from suspected poisoning. He was medically evacuated from the Siberian city of Omsk and transported to Berlin Saturday. The German hospital treating him said in a statement Monday that tests indicate he was poisoned. He remained in an artificial coma in intensive care, the hospital added.

The European Union has called for an investigation, and earlier on Monday, the German government said it was “fairly likely” that Navalny was poisoned and would therefore need special protection.

The Trump administration was largely silent on the matter until Tuesday. Earlier in the day, Deputy Secretary Stephen Biegun “expressed deep concern” about Navalny’s condition in a meeting in Moscow with Russian Foreign Minister Sergey Lavrov, according a spokesperson for the US Embassy in Russia.

US Ambassador to Russia John Sullivan on Tuesday said that the German medical finding “necessitates an immediate, comprehensive, and transparent investigation by the Russian authorities that holds the parties behind this act responsible.”

CNN’s Zahra Ullah, Anna Chernova, Hande Atay Alam, Darya Tarasova, Nectar Gan, Nadine Schmidt, Gianluca Mezzofiore, Amy Woodyatt and Kylie Atwood contributed to this report.