The European Union’s foreign policy chief has said a big build-up of Russian troops near Ukraine’s border means it will only take “a spark” to set off a confrontation.

In a sombre assessment of relations with Moscow, Josep Borrell also said the condition of imprisoned Russian opposition leader Alexei Navalny was “critical” and the 27-nation group would hold the Kremlin accountable for his health and safety.

Despite the developments, Mr Borrell said after a virtual meeting of EU foreign ministers that, “for the time being, there is no move in the field of more sanctions” to be imposed on Russia.

He also said there was no request for a synchronised EU diplomatic move of expulsions in the stand-off between the Czech Republic, an EU member state, and Russia following Prague’s accusation that Moscow was involved in a 2014 ammunition depot explosion.

Josep Borrell
Josep Borrell (Francois Walschaerts/AP)

More dangerous at this time, Mr Borrell said, is the massing of Russian troops, including military field hospitals, and “all kinds of warfare”.

“It is the highest military deployment of the Russian army on the Ukrainian borders ever. It’s clear that it’s a matter of concern when you deploy a lot of troops,” Mr Borrell said. “Well, a spark can jump here or there.”

Initially, he told reporters there were more than 150,000 Russian troops massing on the Ukrainian border and in Crimea, before officials corrected it in the transcript, saying the real figure was more than 100,000.

Nevertheless, Mr Borrell said the risk of further escalation is “evident”.

He declined to say where he got the initial 150,000 number from, but called it “my reference figure”. It was higher than the 110,000 estimate provided by Ukrainian defence minister Andriy Taran on Wednesday.

More than 14,000 people have died in seven years of fighting between Ukrainian forces and Russia-backed separatists in eastern Ukraine that erupted after Moscow’s 2014 annexation of Ukraine’s Crimean peninsula.

The EU has steadfastly opposed the annexation but has been unable to do anything about it.

Efforts to reach a political settlement have stalled and violations of a shaky truce have become increasingly frequent in recent weeks across Ukraine’s eastern industrial heartland known as the Donbas.

Diplomats had expected little chance of immediate new sanctions on Moscow, but they now will seek to apply more pressure through diplomacy.

“Moscow must switch from provocation to co-operation,” German foreign minister Heiko Maas said.

Over the weekend, French President Emmanuel Macron said that while dialogue with Russia is essential, “clear red lines” carrying possible sanctions must also be drawn.

“All in all, the relations with Russia are not improving, but the contrary, the tension is increasing in different fronts,” Mr Borrell said.

“We call on Russia to withdraw their troops.”