MOSCOW, March 18 (Reuters) - Kremlin spokesman Dmitry Peskov, commenting on Alexei Navalny's widow claims that her husband was killed in a Russian prison, said it was not the case, RIA news agency reported on Monday.

Russian authorities say Navalny, President Vladimir Putin's most prominent critic, died on Feb. 16 in an Arctic prison of natural causes.

Navalny's wife Yulia Navalnaya has accused Putin of having him killed. (Reporting by Vladimir Soldatkin)