Russia and Ukraine said yesterday (19 August) that their presidents would meet together with top European Union officials in Belarus's capital of Minsk on 26 August to discuss their conflict over Ukraine, which has plunged relations to an all-time low.

The meeting will put Russia's President Vladimir Putin and Ukraine's Petro Poroshenko in the same room for the first time since a passing encounter in France in June, though Ukrainian officials were at pains to say no face-to-face meeting there between the two men was planned as yet.

>> Read: Ukraine, Russia discuss peace plan

Nonetheless, with a Ukrainian military offensive making inroads against pro-Russian separatist forces in eastern Ukraine, Ukrainian officials were upbeat that the Minsk meeting could be a diplomatic opportunity for Kyiv, and provide a forum for bringing fresh diplomatic pressure to bear on Putin to end Moscow's support for the rebels.

"Today a clear diplomatic roadmap is taking shape. We can come up with new approaches that will allow us to talk about a move from war to peace," Valery Chaly, Poroshenko's top foreign policy aide, said.

Putin will be accompanied at the talks by Belarussian leader Alexander Lukashenko and Kazkahstan's Nursultan Nazarbayev, whose countries also belong to the Russia-led Customs Union which the pro-Western Kyiv leadership spurned in favour of EU integration when it came to power in February.

The EU team will be headed by EU foreign policy chief Catherine Ashton.

A statement from Poroshenko's administration said the meeting would discuss issues related to implementing the landmark association agreement Kyiv signed with the EU, energy security and "stabilising the situation in Ukraine".

But Chaly clearly suggested that Poroshenko would press Putin to end what he views as Moscow's support for, and arming of, the rebels who now seem increasingly in disarray. Moscow denies Kyiv’s charges that it is allowing supplies of heavy weaponry and sending Russian fighters there.

Rebel losses in the past few days appear to have increasingly pushed Putin into a tight corner.

If he remains silent and allows their defeat, he risks losing face before the "hawks" at home, and the Russian people who largely applauded Moscow's annexation of Crimea in March.

But by trying to maintain pressure on Kyiv’s pro-western leaders through further support for the rebels, Putin risks wider economic sanctions from the United States and European Union.

"I hope that this direct format of concrete discussion on many questions including ending aggression (will have results) because no trade and economic questions can be considered without this key question (being addressed)," Chaly said.

Putin's spokesman, Dmitry Peskov, said only that the leaders "will discuss relations between Ukraine and the Customs Union and there will be a number of bilateral meetings."

The Minsk meeting will form part of a hectic round of diplomatic meetings for Poroshenko in the next two weeks around Independence Day celebrations on Sunday, when he hopes to be able to celebrate battlefield successes against the separatists.

Poroshenko will host a key visit to Kyiv by Angela Merkel on Saturday, when he will expect the German Chancellor to voice strong support for his policy to crush the separatist rebellions.

Separately, Poroshenko's website said he had accepted an invitation by the EU to visit Brussels on 30 August, and would attend also a summit of the US-led NATO alliance in Wales in early September, when he may meet U.S. President Barack Obama, his aides said.

"We cannot say for certain yet, but I think that it would be correct if a meeting between the presidents of Ukraine and the United States took place at this summit," Chaly said.

In the meantime, Ukrainian media reported the incursion yesterday of some 40 heavy military vehicles from Russian territory into Ukraine, entering the city of Luhansk.