As Russia celebrated the first anniversary of its Crimean annexation, Ukraine’s president Petro Poroshenko has dismissed as “hope, not reality” the five-week-old Minsk agreement to end hostilities in his country’s east.

After an exchange of views in Berlin with German chancellor Angela Merkel – so “intensive” that they overran by almost an hour – both agreed that the imperfect Minsk deal remained the best hope of a long-term settlement with Russia. But the visiting Ukrainian leader insisted Moscow, not Kiev, was to blame for the failure to date to meet the conditions of the Organisation for Security and Co-operation in Europe, in particular a 48-hour ceasefire and heavy weapons withdrawal.

At a joint press conference Mr Poroshenko praised the German leader for her dedication to the standoff, recalling at least 40 phone calls and 11 meetings since he took office. Mr Poroshenko played down differences between the two over his demand – and Berlin’s dismissal – that Europe provide greater defence support to see off the challenge from Russian-backed separatists.

Never forget

Ms Merkel said Germany would “never forget” the illegal Crimea annexation and that sanctions against Russia were “not a means to an end”. But she reminded her visitor that firm political talks on stepping up EU sanctions would not take place at this week’s summit, but after further legal assessment of the situation in June.

“For now it is about political obligations that there is close agreement between the sanctions and meeting the terms of the Minsk agreement,” she said. “If we concentrate our attention on Minsk I hope we can move it on further.”

Mr Poroshenko was more outspoken before arriving in Berlin, leaving little doubt that he is looking beyond the current uneasy standoff and concerned an attack on Mariupol could follow “at any time”. “The whole world has to understand that Russia is fighting a war against Ukraine, ” he told the Bild tabloid, vowing to press Ms Merkel for radar, drone and night-vision equipment.

He also dismissed a 2018 World Cup in Russia as “unthinkable” in the current circumstances. Asked if she agreed, the German leader said she had her hands full concentrating on 2015.

The Berlin talks were closely watched from Brussels, where EU foreign ministers were meeting. Germany’s foreign minister Frank-Walter Steinmeier agreed the ceasefire in eastern Ukraine was “fragile” but just about holding.

“We cannot let up now – we have to work with all our energy to stabilise what we have achieved to reach the political process laid down in the Minsk agreement,” he said.

Ahead of this week’s summit, European Council president Donald Tusk appeared to come out in favour of extending sanctions against Russia in June.

“What we need now is pressure, no discussion about details or unclear formulations in the [Minsk] agreement,” he told Germany’s Süddeutsche Zeitung daily. “Whoever thinks Putin or the separatists will show goodwill is either naive or sanctimonious.”

Mr Tusk admitted he faces a challenge in the coming months to prevent divisions creeping into Europe’s discussion of further sanctions.