“Europe must not relax” and needs to stand firm on the Ukraine crisis until Russia “shows it is serious” by clearly pulling back its troops from the border, Europe’s foreign ministers have said.

Going into two days of talks, the 28 European Union ministers described the unprecedented crisis unfurling on the bloc’s eastern flank as “very dangerous” but appeared to be hoping to see Moscow take steps to defuse the tension.

“It is really important that Russia shows that it is serious about the de-escalation by moving troops back,” the EU’s top diplomat Catherine Ashton said.

“We’ll be watching with great care what’s happening there.”

British Foreign Secretary William Hague said Russian troops had made “only a token withdrawal” from the border, and there had not been “real de-escalation” by Russia.

“Therefore Europe must not relax,” Hague added.

The two-day meeting is an informal gathering, a regular six-monthly occasion to take stock of foreign policy issues, with no decisions expected.

It opened a day after Russia, for the second time in three days, heaped pressure on Kiev by scrapping discounts on gas that will cause an 81 per cent hike in gas prices for Ukrainians, one of the highest in Europe.

But several ministers agreed that while Europe needed to stand firm in its support for Ukraine, this was not the time to step up pressure by agreeing to fresh reprisals that would entail economic sanctions against Moscow.

“At the moment we have some kind of breathing time, the tension does not increase. We have to benefit from this opportunity to stabilise the political situation,” said Germany’s Frank-Walter Steinmeier.

Hague too, along with his Dutch colleague Frans Timmermans, said the moment was not for so-called “Phase Three” economic sanctions.

But ministers needed to be ready if necessary “because the situation remains very dangerous, very tense,” Hague said.