The single day death toll is the highest in over a month as government troops and pro-Moscow rebels accuse each other of gearing up for a renewed onslaught that would finish off an already tattered February truce.
"We really strongly condemn this escalation of fighting and we call all sides to cease it and to observe the ceasefire," European Commission spokeswoman Catherine Ray told journalists in Brussels.
UN Secretary-General Ban Ki-moon yesterday said he was "seriously alarmed" by the upsurge in violence, adding that the ongoing "ceasefire violations and the resulting loss of life are unacceptable".
"We are concerned by the course of events in recent days which very strongly resembles the preparation for more military action," foreign minister Sergei Lavrov said.
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Lavrov alleged that Ukraine's forces were intensifying their activities in Shyrokine, a flashpoint village 10 kilometres (six miles) from the government-held port of Mariupol.
Ukraine's foreign ministry, however, lashed out at the rebels and their alleged backer Moscow for the uptick in violence.
On the ground, Ukrainian officials reported the death of two soldiers and three civilians, while a rebel commander said five civilians were killed across the conflict zone in the latest surge in violence.
Volodymyr Kolesnyk, a spokesman for the local health department, told AFP that two civilians were killed in overnight shelling in Sartana village some two kilometres (over a mile) northeast of Mariupol.
An AFP journalist in the village saw dozens of buildings destroyed and the roof of one house ripped off.
He said one man was killed and six more civilians were wounded in a Kiev-controlled village close to the rebels' de facto capital Donetsk.
Meanwhile pro-Moscow separatist officials reported the deaths of five civilians in overnight bombardments, three of them in the city of Donetsk.