WASHINGTON (REUTERS) - United States (US) Vice-President Joe Biden will travel to Kiev on April 22, to demonstrate high-level US support for Ukraine, the White House said on Saturday after expressing concern about escalating tensions in the eastern part of the country.

The White House warned Russia against further military action in Ukraine after armed separatists seized government offices in the eastern city of Slaviansk, saying the situation was reminiscent of what happened before Russia annexed Ukraine's Crimea region.

"The Vice-President will discuss the latest developments in eastern Ukraine, where pro-Russian separatists, apparently with the support of Moscow, continue an orchestrated campaign of incitement and sabotage to destabilise the Ukrainian state," the White House said in a statement.

Mr Biden, a top advisor to President Barack Obama on foreign policy issues, has been deeply involved in US diplomatic efforts in Ukraine since protests erupted in Kiev in November.

He will be the highest-level US official to visit the country since the crisis began there. Secretary of State John Kerry visited in early March to show support for Ukraine's leaders after Moscow took control of the Crimea region.

Mr Biden's meetings with Ukrainian government leaders and civil society groups are timed ahead of presidential elections on May 25. He will also discuss energy security issues, the White House said.

"The Vice-President will underscore the United States'strong support for a united, democratic Ukraine that makes its own choices about its future path," the White House said in a statement about Mr Biden's visit.