The United States and Russia failed Sunday to reach a deal on Ukraine after talks in Paris, with US Secretary of State John Kerry calling on Moscow to pull back its forces.
The latest bid to resolve the worst East-West standoff in the post-Cold War era came after Russian leader Vladimir Putin unexpectedly called US President Barack Obama on Friday asking to pursue a diplomatic solution.
Washington and its allies have imposed stinging sanctions on Moscow after it annexed Crimea and massed thousands of troops on the borders of eastern Ukraine.
Russian Foreign Minister Sergei Lavrov said the talks with his US counterpart Kerry in the French capital had been "constructive" and would continue.
After four hours of hastily arranged discussions, Lavrov said the two parties had presented their plans for a de-escalation of the crisis but failed to agree on what had caused it, reiterating Russia's belief that federalism in Ukraine would be key to finding a solution.
Kerry urged Russia to pull back its forces from the borders of Ukraine, and said any talks on the country's future must include Kiev's leaders.
"We will not accept a path forward where the legitimate government of Ukraine is not at the table. This principle is clear. No decisions about Ukraine without Ukraine," Kerry told reporters after the talks.
The top US diplomat said both countries "have differences of opinion about the events that led to this crisis. But both of us recognise the importance of finding a diplomatic solution for the Ukrainian people".
Kerry said the discussions with Moscow would continue "soon".
Washington would work with the new interim leaders in Kiev to ensure the rights of minorities and language rights, Kerry told a press conference.
Moscow's plan would allow parts of Ukraine, a former Soviet republic, to declare Russian as a second official language and secure more independence from Kiev -- a move analysts view as a bid to weaken the authority of what is likely to be a permanent new pro-Western leadership.
"We are convinced that federalism is a very important element of the constitutional reforms (Kiev must implement)," Lavrov said.
"We have to find a consensus, a compromise between the regions of Ukraine." (AFP)