Despite their bitter differences, the pair have managed to keep talking through Merkel's 16 years in office.

Alexei Navalny stressed in an interview with Bild daily that any embargo must not hurt the general Russian population.

Defendant stands accused of gunning down a Georgian national in Kleiner Tiergarten park last year.

"I will not give Putin the gift of not returning to Russia," the opposition leader said.

Prosecutors said the accused killer received orders from "the central government of the Russian Federation."