One national guard member has been killed and about 100 injured outside Ukraine’s parliament, after MPs gave initial backing to reforms for more autonomy in the rebel-held east.
National guardsmen were pelted with fire crackers and petrol bombs as explosions were heard.
MPs had just voted in a rowdy session to approve more powers in areas of Donetsk and Luhansk under control of pro-Russian rebels.
Pushing through greater autonomy for the rebel-held areas is a key part of the Minsk deal, originally signed in February.
During the summer fighting between Ukrainian army forces and the rebels has escalated. But the two sides agreed last week to halt the violence on 1 September, the day children in the region return to school.
Although the number of ceasefire violations appears to have fallen in recent days, a senior official in the OSCE international monitoring mission in Ukraine, Alexander Hug, warned that neither side was respecting the truce.
“Violations have become the norm,” he told Swiss media.
Shortly after 265 MPs backed the first reading of the decentralisation bill in the Ukrainian parliament, the Rada, the protests outside parliament became more intense.
A missile was hurled from the crowd of demonstrators, many of whom were carrying banners supporting ultra-nationalist Svoboda (Freedom) party.
A loud explosion rang out and an AFP reporter described seeing several people covered in blood.
One policeman’s leg was torn off below the knee, Interfax Ukraine reported.