Details remained unclear after more than 12 hours of peace talks in the Belarus capital Minsk, with one source saying there was hope an agreement could be reached and another saying a document would be signed.
But the document, which may be a joint declaration rather than a full agreement, may be signed by lower level envoys rather than by the leaders themselves, the sources said.
Reuters quoted sources as saying that any agreement would however be sent to a "contact group" which includes representatives of the pro-Russian rebels, whose involvement could be crucial.
The discussions came as pro-Moscow separatists tightened the pressure on Kiev by launching some of the war's worst fighting on Wednesday, killing 19 Ukrainian soldiers in assaults near the railway town of Debaltseve.
Fighting has already killed more than 5,000 people, and Washington is now openly talking of arming Ukraine to defend itself from "Russian aggression", raising the prospect of a proxy war in the heart of Europe between Cold War foes.
The summit was held in neighboring Belarus under a Franco-German proposal to try to halt the fighting in eastern Ukraine.
Chancellor Angela Merkel and President Francois Hollande joined Ukraine's Petro Poroshenko and Russia's Vladimir Putin for a longer-than-expected meeting that began early on Wednesday evening and continued well into Thursday morning.
A Ukrainian presidential aide, Valeriy Chaly, had earlier described the four-way talks as "a battle of nerves".
As the talks began, Poroshenko said that without a de-escalation of the conflict and a ceasefire the situation would get "out of control".
The outcome of the talks is expected to influence discussions at an EU summit in Brussels on Thursday, when sanctions against Moscow will be on the agenda.