(Adds comment from White House, details on call with Merkel)
By Steve Holland and Lesley Wroughton
WASHINGTON, Feb 20 (Reuters) - President Barack Obama is urgently considering a range of sanctions against Ukraine after the death toll mounted from violent protests in central Kiev, the White House said on Thursday.
No details were given on the options under consideration or the timeline for decisions, but Obama spoke with German Chancellor Angela Merkel on Thursday to discuss steps to help end the violence.
"The president and senior members of his team have been acting quickly to consider the range of options that are available and acting with a sense of urgency, because of the terrible violence that we saw overnight," White House spokesman Josh Earnest told reporters at a briefing.
Ukraine suffered its bloodiest day since Soviet times on Thursday when more than 20 civilians were killed after three hours of fighting in Kiev's Independence Square, which was recaptured by anti-government protesters.
The European Union agreed on Thursday to impose sanctions on people responsible for violence in Ukraine.
The White House has been urging Ukrainian President Viktor Yanukovich to immediately withdraw security forces and respect the right of peaceful protest. Obama, at a news conference on Wednesday in Mexico, called for a move to a unity government and ultimately, free and fair elections.
"We are outraged by images of Ukrainian security forces firing automatic weapons on their own people," White House spokesman Jay Carney said in a statement.
The United States has limited power to influence Ukraine, but does have some leverage through long-standing security ties with the country, said Damon Wilson, a former senior director for European affairs at the White House National Security Council.
Keeping up the pressure on Ukraine to keep the military out of the political crisis is "at the top of where the United States has some leverage," said Wilson, now executive vice president of the Atlantic Council, a think tank.
However, a senior State Department official said on Wednesday U.S. officials are concerned because they had not been able to reach senior Ukrainian military and intelligence officials over the past several days to warn them about military involvement in the protests.
"We have been trying to re-establish those contacts over the last few days, I would say, and nobody's picking up the phone on the Ukrainian side, which is worrying," the official said. (Additional reporting by Roberta Rampton; Editing by Bill Trott and Mohammad Zargham)