(Adds more comments from Biden, background)
WASHINGTON, June 18 (Reuters) - U.S. Vice President Joe Biden told Ukrainian President Petro Poroshenko on Wednesday the United States would work with its allies to "impose further costs on Russia" if Moscow failed to use its influence to stop separatist violence in eastern Ukraine, the White House said.
Biden's warning came as fighting continued in the east, which has killed 147 Ukrainian soldiers and wounded hundreds more. He said Russia has failed to stop sending weapons and militants across the border.
"The vice president noted that the United States would work with our partners to impose further costs on Russia if it continued on its current course," the White House said in a statement.
The United States and European Union imposed sanctions on Russian individuals and some companies after Moscow annexed Ukraine's Crimea region in March, and have threatened broader economic sanctions on sectors such as energy and mining.
European Union leaders are expected to discuss sanctions at a meeting slated for June 27. Biden and Poroshenko agreed to "stay in touch" ahead of that meeting, the White House said. (Reporting by Roberta Rampton; Editing by Peter Cooney and Ken Wills)