"He has ordered a full investigation, saying the authorities did nothing to stop this crackdown, and were inefficient and they violated the law."
London, May 4 - Pro-Russian protestors Sunday attacked police headquarters in Ukraine's port city of Odessa, forcing release of several people held over Friday's violence, BBC reported.
The clashes came two days after violence in the southern Ukrainian city in which dozens of people were killed.
Hundreds of people gathered outside the building, demanding that those arrested after Friday's unrest be released, the report said.
The victims of Friday's violence were mostly pro-Russian separatists killed when the building they were barricaded in caught fire.
Ukraine's Prime Minister Arseniy Yatsenyuk has accused police of failing to prevent the violence.
He has ordered a full investigation, saying the authorities did nothing to stop this crackdown, and were inefficient and they violated the law.
He, however, said that the unrest was part of a plan fomented by Russia to destroy Ukraine.