Russia's foreign minister has warned that Ukraine's Nato ambitions are threatening to derail peace talks in eastern Ukraine.
Russia and Ukraine said yesterday they are working on a deal to halt months of fighting in eastern Ukraine.
Russian president Vladimir Putin spelled out a seven-point plan for ending hostilities and expressed hope for a breakthrough at talks in Minsk, Belarus, tomorrow.
But Foreign Minister Sergey Lavrov said that statements by senior government officials in Kiev that Ukraine will be seeking to join Nato are "a blatant attempt to derail all the efforts" to seek a peaceful solution in Ukraine.
Pro-Russian separatists have been fighting government troops in eastern Ukraine since mid-April in a conflict that the UN estimates has killed nearly 2,600 people.
Nato leaders are meeting this week at a summit in Wales. As they began gathering, Nato secretary general Anders Fogh Rasmussen accused the Russians of continued meddling in Ukraine despite Mr Putin's proclamation of a peace plan.
"What counts is what is actually happening on the ground," Mr Rasmussen said. "And we are still witnessing, unfortunately, Russian involvement in destabilising the situation in eastern Ukraine. So we continue to call on Russia to pull back its troops from Ukrainian borders, stop the flow of weapons and fighters into Ukraine, stop the support for armed militants in Ukraine and engage in a constructive political process. That would be a genuine effort to facilitate a peaceful solution to the crisis in Ukraine."
Rebels have made substantial advances against Ukrainian forces over the past two weeks, including opening a new front along the coast of the Sea of Azov. That offensive has raised concern that the rebels are aiming to take control of Mariupol, a major port city of about half a million people, and secure a land corridor between Russia and the Crimean Peninsula that Russia annexed in March.
Today, an AP reporter saw three military-type vehicles on fire in Berezove, a village along the main road connecting Mariupol and Donetsk, the largest rebel-held city. Rebel fighters were seen moving nearby, indicating they could be trying to take control of the strategically important highway.