MOSCOW, Sept 21 — Russia’s transport police said on Monday their officers had questioned around 200 people as part of a pre-investigation probe into the case of leading Russian opposition figure Alexei Navalny, and that the probe was still under way.

Russia has not opened a formal investigation into the case despite Berlin saying that laboratory tests in Germany, France and Sweden have determined that Navalny was poisoned in Russia with a Soviet-style Novichok nerve agent.

The transport police also said they had filed requests to Germany, France and Sweden for legal assistance in the case. — Reuters