Heiko Maas, the German foreign minister, has pledged solidarity with the UK, while describing Russia as "a difficult partner".

He spoke ahead of a meeting of EU foreign ministers in Brussels on Monday (19 March), one day after Russian leader Vladimir Putin secured six more years in power and in the wake of British allegations that Russia poisoned a former spy in the UK using a nerve toxin.

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Maas (r): "Russia will remain a difficult partner" (Photo: consilium.europa.eu)

Maas said it was up to Russia and the UK to clarify details of the evidence "bilaterally", but added that "all the information we have suggests there is no alternative plausible explanation" than that Russia did it.

He said Germany and other EU states would make clear they were "firmly on the side of Great Britain".

He added that "dialogue" with Russia ought to continue, however.

"We assume that Russia will remain a difficult partner," he said. "Russia is … needed when it comes to solving major international conflicts. That is why we want to stay in dialogue, but we expect constructive contributions from Russia," he said.

The French foreign minister, Jean-Yves Le Drian, also spoke out.

He said on Monday there was "no other plausible explanation" than that Russia had tried to poison Sergei Skripal, its former spy, and pledged "solidarity with Great Britain".

The British foreign secretary, Boris Johnson, is to brief EU ministers on the issue at Monday's meeting, an EU source said.

The Russian election will also be mentioned, but a more substantial debate on EU-Russia relations will take place either at an EU summit later this week or at another foreign ministers' meeting in the coming months, the source said.

Johnson gave a foretaste of what he might say at Monday's EU gathering going into the event.

He said Russian claims, that Novichok, a Russian nerve toxin used in the attack, could also have come from the Czech Republic, Sweden, the UK itself, or the US were "absurd".

"This is a classic Russian strategy of trying to hide the needle of truth in a haystack of lies and obfuscation", he said.

He said he was "heartened" by EU support so far, adding: "There isn't a single country around the table here [in Brussels] that hasn't been affected in recent times by some form of malign or disruptive Russian behaviour".

He spoke after the Russian ambassador to the EU, Vladimir Chizhov, suggested to the BBC on Sunday that the UK might have poisoned Skripal.

Putin said in Moscow the same day: "It's complete nonsense to imagine that anyone in Russia could resort to such tricks ahead of the presidential elections and World Cup".

Putin result

Preliminary counting showed Putin won 76 percent of the vote in an election that had excluded all serious contenders and that saw a pro-Putin media blitz.

"The election campaign in Russia has been rigged to president Putin's advantage, including government control over the media and opposition parties who are prevented from applying," Swedish foreign minister Margot Wallstroem said on Sunday.

The EU foreign service noted that Europe would not recognise that part of the election held in Russia-occupied Crimea in Ukraine.

EU top diplomat Federica Mogherini added that ministers would pledge political and financial backing for Ukraine on Monday.

Ukraine support

"I was in Kiev exactly one week ago to pass the message of full support both to the full implementation of the Minsk agreements and the non-recognition policy of the annexation of Crimea," she said.

The Minsk peace agreement says Russia must pull out troops and weapons from Ukraine and hand back control of the border to Kiev, among other conditions.

The EU has said it will not relax sanctions on Russia until this take place.

Correction: This story, originally entitled "Russia poisoning is not EU concern, Germany says", had reported that German foreign minister Heiko Maas called the Skripal case a "bilateral" matter. In fact, he pledged solidarity with the UK, but said cooperation on evidence should be handled bilaterally. EUobserver amended the article after a clarification by the German EU embassy