奥巴马敦促普京控制乌克兰分裂分子
US President Barack Obama has urged his Russian counterpart Vladimir Putin to use his influence to make separatists in eastern Ukraine stand down.
美国总统奥巴马敦促俄罗斯总统普京利用他的影响力使乌克兰东部的分离派分子停止活动。
The phone call between the two leaders came as pro-Russian activists continued to occupy buildings in eastern towns.
For his part, Mr Putin rejected accusations of Russian interference, calling the reports "unreliable".
EU foreign ministers said on Monday they would expand a list of names targeted by sanctions.
Tension has been steadily rising since Russia annexed the Crimean peninsula, formerly part of Ukraine, last month.
The move, condemned as illegal by Kiev and the West, followed the ousting of Ukraine's pro-Moscow President Viktor Yanukovych in February.
In other developments
Unconfirmed reports on Russian media, quoting separatists, speak of Ukrainian armour being on the move near the flashpoint towns of Sloviansk and Kramatorsk
At least one separatist checkpoint near Sloviansk reportedly came under fire overnight from unknown gunmen in a car but nobody was apparently hurt
A presidential candidate from eastern Ukraine, Oleh Tsarev, regarded as pro-Russian, appeared before reporters in Kiev with a black eye after being assaulted by protesters as he left a TV studio