Crucial elections should be held in eastern Ukraine by the end of July, the foreign ministers of Ukraine, Russia, Germany and France agreed, but questions remain over Kiev and Moscow's ability to seal the deal, AFP reports.

French Foreign Minister Jean-Marc Ayrault said that the Paris meeting was a "step forward" for the restive region, but his German and Ukrainian counterparts painted a gloomier picture of negotiations.

"We underlined the importance of adopting an electoral law to hold local elections by the end of the first half of 2016," Ayrault said at the close of the meeting.

Ukraine's Pavlo Klimkin, however, repeated Kiev's insistence that there can be no polls in the country's east until a total cessation of hostilities with separatist rebels.

"We must be able to ensure these elections are organized safely, we need our territory to be secure," he said.

Ukraine had proposed measures to reclaim control of the border in order to stop "the entry of arms, munitions, Russian mercenaries and troops, but the Russian side did not want to discuss a number of points in detail," he said, according to AFP.

German Foreign Minister Frank-Walter Steinmeier complained of a lack of engagement on both sides.

"I am not satisfied by the way in which Kiev and Moscow have been leading these negotiations," he said, adding the two sides need to "work together in a more constructive manner."

His Russian counterpart Sergei Lavrov left the meeting without talking to the press.

The four chief diplomats also called for "the release and exchange of all prisoners and people held in illegal detention between now and April 30", Ayrault said.