Ukraine’s newly-installed President Petro Poroshenko is set to remake a governing team which will handle the crisis with Russia, with talks on gas prices today providing an early test of his new relationship with Russia’s Vladimir Putin.

Poroshenko’s swearing-in as President at a pomp-filled, but relaxed, ceremony on Saturday conveyed the feeling that a line had now been drawn under six months of unprecedented and bloody upheaval which toppled his predecessor, Viktor Yanukovych.

Poroshenko’s blunt refusal to accept the loss of Crimea puts him further at odds with Putin

But behind the euphoria that Ukraine might now, at last, start to “Live in a new way”, as Poroshenko’s campaign slogan has promised, lies the reality of seething separatism in the east in which Ukraine sees Moscow’s hand, and Russia’s opposition to his plans to lead Ukraine into mainstream Europe.

Poroshenko’s blunt refusal to accept the loss of Crimea in a combative inaugural speech puts him further at odds with Putin. An indication of whether Putin is ready to give the 48-year-old businessman-politician some early breaks or test him in his first days in office may come in trilateral talks in Brussels today aimed at solving a dispute over the price of Russian gas.

Russia has threatened to cut off supplies to its neighbour, a major gas transit route to the EU, if it fails to pay its debts to Gazprom by tomorrow. In early steps to install key allies, Poroshenko is expected in the coming days to name new foreign and defence ministers.

The rebellions, in which pro-Russian separatists have declared “people’s republics”, have claimed scores of lives in clashes between government forces and armed militias.

Meanwhile militia leaders declared on Saturday they would not give up their fight.