EU foreign ministers on Monday agreed in principle to back a French-German proposal to sanction Russian officials over the poisoning of opposition leader Alexei Navalny.

The agreement came at a meeting in Luxembourg where France and Germany were due to outline a proposal for sanctions, made last week after an investigation found that Navalny was poisoned with the chemical nerve agent Novichok. The two countries believe that the poisoning could only have happened with the involvement of Russian authorities.

Navalny, a fierce critic of President Vladimir Putin and prominent anti-corruption campaigner, fell ill on a domestic flight in Siberia on Aug. 20 and was transported to Germany for treatment in a comatose state two days later.

The speed with which Europe's two main powers have agreed to push ahead with sanctions suggested a hardening of the bloc's diplomacy towards Moscow. It contrast to 2018, when it took almost a year for the European Union to agree to sanctions against Russians following a nerve agent attack on a Russian spy in Britain.

Austria's foreign minister, Alexander Schallenberg, whose country is one of Russia's closest allies in the bloc, said there could not be a "return to business as usual" and that Moscow had failed to help clear up doubts about the poisoning.

Blood samples taken from Navalny confirmed the presence of a nerve agent from the banned Novichok family, the Organization for the Prohibition of Chemical Weapons (OPCW) said last week.