The European Union on Thursday agreed to impose a travel ban and asset freeze on Ukrainians with "blood on their hands", said Italian Foreign Minister Emma Bonino.
An EU diplomat said the number of people on the list however "will depend on developments on the ground".
But there will be sanctions, said the source. "There was a political commitment to sanctions" agreed by foreign ministers from the 28-nation bloc.
Work on establishing a list of people deemed responsible for human rights violations, violence and excessive use of force would start Friday, the source said.
Bonino said after Ukraine crisis talks in Brussels with her EU counterparts that the sanctions would be imposed "very rapidly in the next hours".
She said EU nations also agreed to offer medical assistance and visas to the injured and to dissidents.
The decision to impose sanctions was taken in agreement with three EU envoys currently in Kiev, the foreign ministers of France, Germany and Poland -- Laurent Fabius, Frank-Walter Steinmeier and Rodoslaw Sikorski.
The three held several hours of talks with President Viktor Yanukovych and with the three main leaders of the opposition.
Diplomats said the ministers meeting in Brussels had also agreed to suspend the export of anti-riot equipment.