Russian opposition leader's arrest "very disturbing", Dutch FM says

The arrest of Russian opposition leader Alexei Navalny is "very disturbing", Minister Stef Blok of Foreign Affairs said on Twitter on Monday.

"I call upon the Russian government for his immediate release and to bring those responsible for the attempt of his life to justice," Blok said.

Navalny, an outspoken opponent of Russian president Vladimir Putin, fell seriously ill in August after he was poisoned with a Novichok nerve agent. Over the past months he has been recuperating in Germany.

The opposition leader returned to Russia over the weekend, where he was immediately arrested.