European Union (EU) foreign ministers backed a Franco-German plan on Monday to impose sanctions on Russians suspected of poisoning Kremlin critic Alexei Navalny with a nerve agent, diplomats said.

Berlin and Paris made their proposal at a meeting of EU foreign ministers in Luxembourg. They say they have not had a credible explanation from Moscow for what the Organization for the Prohibition of Chemical Weapons (OPCW) said was the presence of the banned Soviet-era nerve agent Novichok in Navalny's body.

The sanctions are not expected to be approved immediately, as legal texts must be prepared and cleared by experts from the 27 EU states.

The Kremlin denies any involvement in the case and says its doctors found no evidence that a nerve agent was used.

Navalny, a politician and staunch critic of Russia's president Vladimir Putin, fell ill on a flight back to Moscow from Siberia on 20 August and was taken to a hospital in Germany. Tests have shown that Russia's opposition leader Alexei Navalny was poisoned by Novichok nerve agent, claimed a spokesperson for the German government.