German Chancellor Angela Merkel on Friday called on Russian President Vladimir Putin to accept the OSCE's assessment on Ukrainian presidential elections this weekend.
"I expect Russia to respect the doubtlessly objective assessment of the OSCE -- after all it is a member of the organisation," Merkel told newspaper the Saarbruecker Zeitung.
A presidential poll is scheduled for Sunday in Ukraine, where pro-Russian separatist militias control several eastern towns, with voting to be monitored by the Organisation for Security and Cooperation in Europe (OSCE).
Merkel said all sides should respect the assessment of the election to be issued by the OSCE, which is to send one of its largest ever observer missions.
"Unfortunately Russia, despite an invitation, has declined to send observers to the OSCE mission," said Merkel, who has been in regular phone contact with Putin since the crisis began.
Asked what she thought Putin's motives were amid the worst East-West standoff since the Cold War, she declined to "speculate".
But she added: "We're seeing that the Russian leadership is finding it difficult to accept that the sovereign country of Ukraine is choosing its own self-determined path.
"Our position is that Ukraine can and should freely decide what it wants. Democratic presidential elections on May 25 are an important part in this."
German Foreign Minister Frank-Walter Steinmeier said the previous day that even those in Ukraine who oppose the Kiev government should have an interest in supporting the fairest election process possible.
"Everyone who rejects the legitimacy of the current Ukrainian leadership must have an interest in new leaders being legitimately chosen, and this can only come through elections," he said.