Officials in Ukraine have begun preparations for presidential elections as early May 25, even as the location of the country's president remains unknown.
However, Moscow said elections should be delayed until after the conclusion of constitutional reforms that were agreed Friday.
“Appointing the elections for May 25 is already a shift away from the agreement,” Russian Foreign Minister Sergei Lavrov told reporters.
Ukraine is being governed by an interim government, led by parliament speaker Oleksandr Turchinov, while the whereabouts of Viktor Yanukovych remain unknown.
In addition to the April 4 deadline to register, candidates must publish details of their assets, income, expenses and financial obligations within three days of registration.
Peter Jeary of NBC News contributed to this report.