Shelling in rebel-held parts of east Ukraine killed at least 12 civilians as a top leader of pro-Russian rebels rejected Ukrainian legislation meant to end the unrest by granting self-rule to large swathes of the east.
The city council of Donetsk, the largest rebel stronghold, said that shelling killed two people in the city and wounded three others.
In a separate statement, the press centre for Kiev's military campaign in the east said that at least 10 civilians in the town of Nyzhnya Krynka, 20 kilometres east of Donetsk, had been killed by shelling.
Since a ceasefire imposed on September 5, the fighting in Donetsk has been primarily limited to the north of the city, where many residential neighbourhoods have been caught in the crossfire of battles centred on the government-controlled airport.
On Wednesday, an AP reporter in that area of Donetsk saw the remains of what appeared to be a Grad rocket in a burned-out building. There was one body visible at the scene.
The ceasefire has been much violated from the start and civilian casualties have continued to rise, adding to the estimated 3,000 people killed since fighting started in April.
On Tuesday, the Ukrainian parliament took a step to resolve the crisis by passing laws that would grant greater autonomy to rebel-held parts of the east, as well as amnesty for many of the separatists, a major concession to both Moscow and the rebels.
But in an interview with the Associated Press in Donetsk, rebel leader Andrei Purgin said that the separatist leadership was not willing to allow Donetsk and Luhansk to remain part of Ukraine.
"We perceive this as a document in which we can find certain points to start a dialogue," Purgin said. "But there is a red line we cannot cross: we do not accept any political unions ... with Ukraine. No federative, no unitary structure."
The laws passed by the Ukrainian parliament call for three years of self-rule in parts of eastern Ukraine and for local elections in December. They grant concessions that were not previously offered by the Ukrainian side, such as local oversight of court and prosecutor appointments and local control of police.
But Purgin insisted that the rebel leadership would settle only on full independence from Ukraine.
"We are unable to join the Russian Federation directly, so we will build our own country," he said.
Purgin's comments, echoed by other leaders on Wednesday, could undermine peace talks that are under way in the Belarusian capital of Minsk between Ukraine, Russia and the Russia-backed rebels.
The comments are also in striking contrast to the Russian foreign ministry's positive reaction to the legislation, which it called a "step in the right direction".
The legislation "creates the foundation for launching a substantive constitutional process in Ukraine, including the start of a dialogue intended to help national reconciliation and accord in the country", the ministry said in a statement.
Ukraine and the West have repeatedly accused Russia of fuelling the separatists with personnel, arms and expertise. Moscow denies those claims.