BRUSSELS: The European Union's top diplomat said on Tuesday that Russia's government was increasingly authoritarian and showed no tolerance of democratic rule of law, warning that a new round of sanctions was a possibility.

"They are merciless," EU foreign policy chief Josep Borrell told the European Parliament after visiting Moscow last week to plead for the release of Kremlin critic Alexei Navalny.

"The current power structure in Russia, combining vested economic interests, military and political control, leave no opening for democratic rule of law," he said.