Donald Tusk says it is first time ‘someone on the order of Russia’ has sought to attack US citizen in Nato country

A Russian plan to kill a Ukrainian American citizen in Warsaw was thwarted by Poland before it could be carried out, the Polish prime minister has said.

Donald Tusk said it was the first time that “someone on the order of Russia” had sought to attack a US citizen on the territory of another Nato country.

Intelligence agencies say deadly toxin in skin of Ecuador dart frogs found in Navalny’s body and highly likely resulted in his death

• What is dart frog toxin, which is said to have been used to kill Alexei Navalny?

Alexei Navalny, the Russian opposition leader, was killed by dart frog poison administered by the Russian state two years ago, a multi-intelligence agency inquiry has found, according to a statement released by five countries, the UK, France, Germany, Sweden and the Netherlands.

The US was not one of the intelligence agencies making the claim.