Protesters have thrown "several" explosive devices outside Ukraine's parliament in the capital Kiev, killing at least one policeman and wounding at least 90 people, according to Interior Minister Arsen Avakov.
The unrest erupted on Monday shortly after parliament backed the first reading of reforms to give greater autonomy to the separatist east as part of a peace deal signed in February.
Anton Gerashchenko, an interior ministry advisor, said attackers had thrown a hand grenade at National Guard troops in what he called an "act of provocation".
Some of the injured, most of whom were in uniform, were bleeding and lying on the ground in front of the parliament. At least one photographer was lightly injured.
Protesters also fired at least one smoke grenade that sent up a thick cloud of black smoke outside the building. Tear gas was used by both sides, the AFP news agency reported.
The constitutional reforms are required under the terms of a Western-backed deal reached in the Belarussian capital Minsk, which called for Kiev to implement "decentralisation" by the end of this year.
But some critics have branded the moves "un-Ukrainian".
A total of 265 legislators voted in favour of the draft legislation at a stormy session of parliament.
Kiev's Western allies see the reforms as a way of trying to end the armed conflict in the east that has claimed more than 6,800 lives over the past 16 months.
The bill has sparked heated debate in Ukraine where opponents see it as an attempt to legalise the de facto rebel control of part of the former Soviet country's territory.
The reform bill grants more powers to regional and local legislators, including in the eastern areas currently under rebel control.
But contrary to the expectations of separatists, it does not definitively hand the largely industrial eastern region the semi-autonomous status that the rebels were seeking.
According to the text of the draft legislation, the region's status needs to be defined by a separate law.
|Protesters fired at least one smoke grenade that sent up a thick cloud of black smoke outside the building [Reuters]