Russia's foreign minister has urged those holding a new round of talks on easing Ukraine's crisis to push for a ceasefire between Ukrainian government troops and pro-Russian separatists.

Foreign minister Sergey Lavrov also said Russia would not intervene militarily in Ukraine, defying reports by the Ukrainian government, Nato and Western nations that Russia has already sent troops, artillery and tanks across Ukraine's south-east border to reinforce the separatists.

"There will be no military intervention," Mr Lavrov told students at Moscow State Institute of International Relations, the first day of classes for schools and universities across the country.

"We call for an exclusively peaceful settlement of this severe crisis, this tragedy."

He said the priority of the so-called contact group at the talks in Minsk, the Belarusian capital, should be reaching agreement on an immediate, unconditional cease-fire.

The group, which last met in late July, includes representatives of Ukraine, Russia and the Organisation for Security and Cooperation in Europe (OSCE). A separatist leader, Andrei Purgin, is also due to take part.

Mr Purgin told the Interfax news agency that the separatists' priority was to win recognition of their independence in eastern Ukraine, which has a large Russian-speaking population.

He said they also were willing to discuss the exchange of prisoners and a temporary ceasefire.

Fighting in eastern Ukraine between the separatists and the Ukrainian government in Kiev began in mid-April, a month after Russia annexed Ukraine's southern peninsula of Crimea.