Washington, Sep 12 (IANS): The US will deepen and broaden sanctions in Russia's financial, energy, and defence sectors "in response to its illegal actions in Ukraine," US President Barack Obama said Thursday.

These measures would increase Russia's political and economic isolation, especially in areas of importance to Russian President Vladimir Putin and those close to him, said Obama, adding that his administration would outline the specifics of the new sanctions Friday, Xinhua reported.

The US is implementing the new round of punitive measures "in light of Russia's actions to further destabilise Ukraine over the last month, including through the presence of heavily armed Russian forces in eastern Ukraine", Obama said in a statement.

The US move came after the European Union announced fresh sanctions against Russia's financial and energy sectors earlier in the day. The new sanctions came despite that the Ukrainian government and rebels inked a ceasefire agreement last week in Minsk, capital of Belarus. The deal was expected to pave the way for political settlement of the Ukraine crisis.

"We are watching closely developments since the announcement of the ceasefire and agreement in Minsk, but we have yet to see conclusive evidence that Russia has ceased its efforts to destabilise Ukraine," Obama said.

The US president said he encouraged Putin to work with Ukraine and other international partners, within the context of the Minsk agreement and without setting unreasonable conditions, to reach a lasting resolution to the conflict.

Obama reiterated that the sanctions against Russia could be rolled back if it fully implemented its commitments, but also warned of imposing tougher costs on Russia if it continued its " aggressive actions and violations of international law."