The German foreign minister, Frank-Walter Steinmeier, has said sanctions should be used as a threat against Ukraine's government unless it finds a political solution to its long-running dispute with the opposition.
The Social Democrat minister's comments strike a different tone from the line taken so far by Chancellor Angela Merkel, who last week ruled out imminent sanctions.
"I think we must now show sanctions as a threat," Steinmeier told Germany's ARD television late on Monday, adding that Germany had to be ready to act if the situation did not improve.
Ukraine has been hit by more than two months of unrest following a decision by President Viktor Yanukovich not to pursue trade and other deals with the European Union.
Ukraine is now in a tug-of war between Russia and the west.
The US and EU are in preliminary discussions about possible financial assistance for Ukraine once a new government is formed, a state department spokeswoman said on Monday.
Opposition leader and former boxer Vitali Klitschko visited New York earlier this week, he said, to draw attention to the political crisis in the former Soviet republic.
"I just want to spread the word and say what is going on in the Ukraine and point out that we do have an issue that unfortunately could become a civil war, and much more people could die," Klitschko told the Associated Press in an interview on Monday.
"And we could lose another country, Ukraine, to dictatorship."
The only way out, said Klitschko is for the government to resign and for early parliamentary elections to be held.
"I'm worried for the safety of everybody, including my brother," Klitschko said.
"This is not a joke. It's serious. It's about life and death."
He added: "It's critical, and the situation can change in the blink of an eye."
Source: The Guardian