SARTANA, Ukraine (AP) - Fighting intensified Tuesday in eastern Ukraine as pro-Russia rebels and Ukrainian troops sought to extend their gains ahead of crucial peace talks, and the government accused the separatists of shelling a town far behind the front lines, killing 12 people and wounding scores.
Germany, which has joined with France to try to broker a peace deal, urged Russia and Ukraine to compromise and called on the warring parties to refrain from hostilities that could derail a four-way summit Wednesday in Minsk, Belarus.
Ukrainian President Petro Poroshenko said the talks were "one of the last" opportunities for ending the fighting that has killed more than 5,300 people since April.
Poroshenko told parliament in Kiev that the separatists launched a rocket strike Tuesday on the town of Kramatorsk, more than 30 miles from the nearest front line, hitting a regional military command center with the first salvo and then striking a nearby residential area.
Rebels denied any involvement in the attack and said it was a "provocation" by the Ukrainian authorities. Kramatorsk was the site of major fighting until July, when pro-Russian separatists retreated.
The government-controlled Donetsk administration said 12 people were killed by the barrage in Kramatorsk and 64 were wounded, including 29 civilians.
Photos on the local Donetskiye Novosti website showed an artillery shell embedded in the ground next to a residential building and two bodies lying nearby.
Further south, the volunteer Azov battalion, loyal to the government in Kiev, said on social media Tuesday that it captured several villages northeast of the strategic port of Mariupol, pushing the rebels closer to the border with Russia.
However, a rebel spokesman, Eduard Basurin, insisted in a televised news conference that the rebels had not retreated.
The pro-government volunteers said rebels shelled the village of Kominternove, east of Mariupol, causing unspecified civilian casualties. An Associated Press reporter at a government checkpoint between there and Mariupol heard of fighting several miles away and saw two ambulances and four trucks carrying Ukrainian troops from the direction of Kominternove toward Mariupol.
Oleksandr Turchynov, chairman of the Ukrainian Security and Defense Council, visited the area Tuesday and said the government offensive aimed to bolster the defenses of Mariupol and "protect civilians from artillery strikes."
The rebels reported advances, too. Basurin said they had surrounded the railway hub of Debaltseve, the focus of fierce fighting in the past weeks, cutting it off from a major highway.
At least seven Ukrainian troops were killed overnight in the east, military spokesman Anatoliy Matyukhin said, while in the rebel stronghold of Donetsk, which faces frequent shelling, two civilians were reported killed and 12 injured.
Amid the escalating hostilities, the insurgents announced a call-up of new volunteer recruits in Donetsk, following a pledge by separatist leader Alexander Zakharchenko to strengthen his forces to 100,000 men.
Rebel official Arkadiy Fedoseyev said the separatists were recruiting "tank drivers, mechanics, technicians and repairmen."