Moscow ? Germany’s foreign minister warned Thursday that the assassinations of two vocal Kremlin critics had the potential to damage Moscow’s reputation and urged Russia to help with the investigations into their deaths.

His Russian counterpart, Sergey Lavrov, warned against “politicizing” the case.

German Foreign Minister Frank-Walter Steinmeier said Alexander Litvinenko’s death Nov. 23 in London and the October killing of Russian investigative journalist Anna Politkovskaya “have the potential to damage Russia’s reputation very badly.”

Litvinenko, an ex-KGB agent, died after being poisoned with rare, radioactive polonium-210. He blamed Russian President Vladimir Putin for the poisoning on his deathbed – accusations the Kremlin strongly has denied. Litvinenko said Kremlin agents were concerned about his efforts to investigate Politkovskaya’s murder.