The Russian Komsomolskaya pravda newspaper briefly published a figure indicating a Russian death toll of nearly 10,000 soldiers from the fighting in Europe -- then quickly deleted the information.
The online report on March 20 cited the Russian Defense Ministry as reporting that 9,861 Russian soldiers had died since the start of the war on February 24.
The information was seen in an archive version seen by news outlets, including dpa and The Wall Street Journal, on March 21.
The pro-Kremlin newspaper did not immediately make a statement about the report or its deletion.
Russia has officially confirmed just 498 deaths, a figure given early in the conflict without updates.
U.S. and Ukrainian officials have estimated the deaths at more than 7,000, with some estimates going near 10,000, although casualty figures in the war are impossible to independently confirm.
Yaroslav Trofimov of The Wall Street Journal wrote on Twitter that "Either [the newspaper's website] KP.ru has been hacked or someone there got the leaked numbers and posted them."