EU foreign policy chief Josep Borrell will visit Moscow early next month to press the Kremlin on the arrest of Alexei Navalny, diplomats said Monday, as Brussels weighs fresh sanctions.

"Borrell will go to Moscow in early February to deliver a clear message from the EU," a senior diplomat told AFP, despite earlier calls from several member states for the trip to be scrapped.

The visit was confirmed during a meeting in Brussels where foreign ministers from the 27 nations debated their response to the arrest of Kremlin critic Navalny and crackdown on demonstrators.

The diplomats discussed slapping sanctions on the Kremlin after pressure from several capitals for a tough line, but decided it was "premature" to impose the punitive measures, one diplomat said.

"Sanctions are a possible tool, but it is necessary to wait to see what happens in Moscow," a second diplomat said.

European diplomats had earlier said Brussels was expected to hold off on sanctions until Navalny goes to court on February 2 to see if the Kremlin puts him behind bars for an extended term.

The anti-corruption campaigner is facing three-and-a-half years in jail for breaching the conditions of an earlier suspended sentence while recovering in Germany from a near-fatal poisoning with a Novichok nerve agent.

His arrest on returning to Russia unleashed a wave of protests on Saturday that saw baton-wielding riot police detain more than 3,500 people.

The EU has called for the immediate release of Navalny and of peaceful protesters detained during the nationwide rallies.

Lithuanian Foreign Minister Gabrielius Landsbergis insisted as he entered Monday's meeting that the bloc "needs to send a very clear and decisive message that this is not acceptable".

Borrell has insisted on sticking to his planned trip, which would be the first to Moscow by an EU foreign policy chief since 2017, despite opposition from several countries.

Diplomats argued that the Kremlin could use the visit to show the EU is continuing with "business as normal" despite the clampdown on the opposition.

Brussels has already hit Russia with sanctions for annexing Crimea and fuelling the Ukraine conflict.

In October, the bloc put six senior Russian officials on an assets freeze and travel ban blacklist over the "assassination attempt" on Navalny.

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