Russia using gas-price crisis to bully EU, Ukraine says

"Prices are also formed based on the political environment and if Russia produces a narrative of crisis, prices react to that", she added.

Gas prices in Europe have more than tripled since the start of the year amid low stocks and a global surge in demand.

Nord Stream 2 is Russia's new gas pipeline to Germany, which is meant to have an independent operator who also lets non-Russian suppliers use it under EU law.

"We can't allow Russia an exception from European rules on this," Stefanishyna said.

But for all that, Russia is pushing to operate the pipeline as its own monopoly, harming EU energy security by enabling it to cut gas to Western allies such as Poland and Ukraine in future.

It is also withholding gas to aggravate market tension, not just according to Ukraine but also according to a group of cross-party MEPs, who recently complained that Russian firm Gazprom was refusing to guarantee additional volumes for winter "despite available information" that it had "sufficient production capacity".

When asked about it on Wednesday, Russia's EU mission said Stefanishyna's accusation was unfounded because gas prices were set by global market forces.

And Kremlin spokesman Dmitry Peskov recently played nice. "Is it possible to get more gas from [Russian state-owned firm] Gazprom and pump it in there? It's possible. Gazprom is ready", he said on Monday.

EU leaders plan to discuss the gas-price spike at their next summit in October.

But for Stefanishyna, the need for Nord Stream 2 to be bound by EU law should already be spelled out in a declaration at an EU-Ukraine summit, which falls next week.

And Germany should clarify a promise it made to impose new EU sanctions on Russia if it abused Nord Stream 2, she added. "It's really important we should have a common understanding of red lines, because the red lines for us and for Germany ... could be different," she said.

Ukraine currently transits most Russian gas exports to the EU.

And Russia's behaviour on the battlefields in east Ukraine and in Russia-occupied Crimea has also bolstered its "crisis-narrative" on gas-supply security.

A few months ago, it marched an invading force to Ukraine's eastern frontier, before retreating.

But the Russians left large weapons systems near the border "at their disposal" in case Moscow wanted to escalate again, Stefanishyna said.

It also held sham elections in Crimea in its bid to cement the occupation there, with Ukraine calling on the EU to blacklist some 50 officials who organised the vote on human-rights abuse grounds, Stefanishyna added.

And things took a step back when Russia recently declined to extend the life of a 22-man international monitoring mission on the border between Russia and Russia-occupied regions in east Ukraine.

The Swedish foreign office told EUobserver it "deeply regretted" the Russian move, speaking in Sweden's capacity as chair of the Organisation for Security Cooperation in Europe (OSCE), an intergovernmental body providing the monitors.

"Sweden has addressed the continuous violations of the ceasefire that are a particular concern. The same is true of the freedom of movement for civilians affected by the conflict," it added, in a snapshot of the seven-year long, low-intensity war.

"A full ceasefire would also allow for other measures that would build confidence and improve the security situation, such as de-mining and the withdrawal of heavy weapons," it said.

A second OSCE monitoring mission, which operates along the contact line in east Ukraine, is to stay in place for now.