WASHINGTON (AP) — Ukrainian President Petro Poroshenko has told Vice President Joe Biden that Ukraine’s offers for cease-fire talks were all rejected by either Russia or pro-Russian separatists.

Biden and Poroshenko spoke by phone on Thursday. The White House says Poroshenko told Biden that Ukraine proposed multiple locations for negotiations in Ukraine, Russia and other countries. He says all were refused.

The separatists have said Ukraine proposed unacceptable conditions, including a demand rebels first lay down their weapons before talks are restarted.

The White House says Biden told the Ukrainian leader that the U.S. and other nations are discussing holding Russia accountable for supporting the separatists with heavy weapons and equipment that has flowed across the Russian-Ukrainian border. The two also discussed the need for independent monitors to help oversee a potential cease-fire.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.