Ukraine's acting President Oleksander Turchynov has said the Ukrainian government is "not against" a referendum on the country's form of government.
In televised comments this morning, Turchynov said a referendum could be held at the same time as presidential elections scheduled for May 25.
Turchynov said he was sure the majority of Ukrainians would back a united, independent country.
In Moscow, Russian Foreign Minister Sergei Lavrov said more information was needed on the referendum mooted in Kyiv.
The holding of such a referendum has been one of the key demands of pro-Russia separatists who have occupied state buildings in the east of the country.
There were no signs the separatists were preparing to comply with a government ultimatum to hand over their weapons and leave the state buildings by early morning today.
The government had threatened a "large-scale" military operation if the separatists failed to comply.
Stream from Horlivka in E Ukraine, pro-Russian activists attempt to storm police stn, smash windows & break inside: http://t.co/ys0fBFpNkK
— Laura Mills (@lauraphylmills) April 14, 2014
!!!Breaking News!!!
Our news desk has reported a potentially interesting development in Kyiv:
Govenor of #Donetsk Sergiy #Taruta announces special operation regime, but still no sign of it on the ground #Donbas
— Harriet Salem (@HarrietSalem) April 14, 2014
With tensions rising over Ukraine, Russia test launches a new ICBM and Putin gives himself a pay rise
— tom balmforth (@BalmforthTom) April 14, 2014
1/2 Was just taken at gunpoint into the barricades here in Sloviansk, placed on my knees, surrounded by guns at me.
— GrahamWPhillips (@GrahamWP_UK) April 14, 20142/2 Had to talk out of what I felt was real danger. Then guys are ok, apologise to me, say `this is war in Ukraine, please understand that`
— GrahamWPhillips (@GrahamWP_UK) April 14, 2014Hostility towards journos in E #Ukraine v high MT @GrahamWP_UK Was just taken at gunpoint...placed on my knees, surrounded by guns at me.
— Alexander Marquardt (@MarquardtA) April 14, 2014
#Donetsk Governor Serhiy Taruta says anti-terrorist operation against pro-Russian forces underway in eastern #Ukraine http://t.co/gfmUEct0sO
— Christopher Miller (@ChristopherJM) April 14, 2014
It is easy to find whether a journo is pro-West or pro-#Russia: a former will say #Kharkiv #Slovyansk a latter will say #KharkOv #SlAvyansk.
— Ivan Nechepurenko (@INechepurenko) April 14, 2014
This photo of the "press conference" that just happened now just retweeted by the US Ambassador to Ukraine: pic.twitter.com/xHLVP72BU0
— Shaun Walker (@shaunwalker7) April 13, 2014
@shaunwalker7 All 3 accused of involvement in the Maidan shootings - a historic crime that needs full investigation not specious accusations
— Geoffrey Pyatt (@GeoffPyatt) April 13, 2014