WASHINGTON, June 23 - U.S. President Barack Obama urged Russian President Vladimir Putin on Monday to support peace in Ukraine and said Moscow would face further "costs" if it did not take steps to reduce tensions in the country, the White House said on Monday, Reuters reported.

"The president spoke to President Putin and once again urged him to support peace instead of allowing the provision of arms and materiel across the border and continuing support for militants and separatists who are further destabilizing the situation in Ukraine," White House spokesman Josh Earnest told reporters.

"Russia will face additional costs if we do not see concrete actions to de-escalate the situation," he said of Obama's message to Putin.