In addition to Germany, France and Sweden have also determined that the Russian opposition leader Alexei Navalny has been poisoned with a Novichok nerve poison.

Laboratories in those two countries have independently confirmed Germany’s test results, says Chancellor Angela Merkel’s spokesman Steffen Seibert.

“We reiterate the call to Russia to explain the events. We are in close contact with our European allies about further steps,” Seibert said in a statement.

Navalny, 44, a prominent critic of Russian President Vladimir Putin, is in a German hospital after becoming unwell on a flight from Siberia to Moscow on August 20.