Washington: US Secretary of State John Kerry accused pro-Russian separatists on Wednesday of attempting "a blatant land grab" in fresh fighting in eastern Ukraine.
The US was "particularly concerned" by a rebel initiative to "attempt to gain control of a very significant rail juncture" in eastern Ukraine in violation of a September ceasefire deal, he said, calling it "an effort to try to broaden the amount of territory that is being held."
Speaking after meeting EU foreign policy chief Federica Mogherini, Kerry said there had been about a 500-square-mile (1,300 sq kms) extension of the line of control which demarcates the rebel-held territory from the rest of Ukraine.
"So this is a blatant land grab and is in direct contravention to the Minsk agreements which they signed up to," Kerry added, referring to the ceasefire deal.
He described the fresh fighting as "an alarming situation" adding, "the United States continues to support Ukraine`s territorial integrity and we condemn all actions that are aimed at undermining its sovereignty."
Kerry added that he and Mogherini had agreed to "do all that we can" to help Ukraine deal with a worsening economy.
The US and EU have together imposed sanctions on Russia, part of an economic downturn in the Russian economy.
The EU sanctions are due to be reviewed in March after one year in force, but Mogherini stressed "any kind of decision on sanctions is going to be based only on the full implementation of the Minsk agreement."
She urged Moscow to fullfil all the commitments it had undertaken in signing the accords in the Belarus capital last year.