The Ukrainian army said Friday that its soldiers came under artillery fire from the Russian side of the border overnight and were attacked by Russian-backed separatists in several other places in Ukraine’s restive east.
A spokesman for Ukraine's Security Council also said 13 soldiers had been killed in the last 24 hours, taking the total death toll to 325 since the start of fighting against the rebels, who are seeking independence for the Russian-speaking Donbass region.
In a statement Friday, the headquarters of Kiev’s so-called counter-terror operation in the east listed at least seven locations where it said rebels attacked Ukrainian troops. Kiev also claimed that attacks on two locations near the border were supported by artillery fire from Russia.
In response, Russia said that about 40 mortar shells fired by Ukrainian forces had fallen in the province of Rostov near the border with eastern Ukraine, state-run Ria Novosti news agency reported.
"Those who shot from Ukraine carried out the shooting purposefully with an intent to kill Russian law enforcement officials," said Russia's Investigative Committee, which answers directly to President Vladimir Putin.
Moscow has vehemently denied a role in the conflict between pro-Russian separatists and government troops. The fighting erupted after Russia annexed Ukraine’s Crimean Peninsula in response to a pro-European uprising in Kiev that toppled the Russian-allied president.
But the United States and many of its Western allies allege that Russia continues to provide heavy arms to the Ukraine separatists, an accusation that has carried extra weight since Malaysian Airlines flight 17 was shot down over eastern Ukraine last week.
On Friday, the Pentagon warned that the movement of heavy-caliber Russian artillery into Ukraine was imminent. A Pentagon spokesman also said Russian troops were once again building along the border with Ukraine, hinting at the possibility of direct intervention. Close to 12,000 Russian troops are currently located there.
State Department spokeswoman Marie Harf said a day earlier that the U.S. had evidence Russia was firing artillery from within Russian territory to attack Ukrainian military positions. But Washington has not released evidence supporting those allegations, allowing Moscow to brush them off.
Also Friday, European Union ambassadors reached a preliminary deal on stepped-up sanctions against Russia, targeting its access to European capital markets and trade in the defense sector, dual-use goods and sensitive technologies.
EU spokeswoman Maja Kocijancic said the proposals were transmitted to EU officials to codify into regulations, with the ambassadors scheduled to meet again Tuesday to review the results.
The ambassadors also ordered EU-wide asset freezes and travel bans for 15 more Russians and pro-Russian Ukrainians who are accused of undermining Ukraine's territorial integrity, the EU said in a news release. Eighteen businesses or entities will also now be subject to EU sanctions for the same reason, the release said.
Meanwhile, shelling and attacks continued in Ukraine, and more Ukrainians are fleeing the border region to escape the fighting. According to the latest United Nations report, more than 230,000 Ukrainians have fled, many of them to Russia.
Ukrainian forces are trying to close in on the rebels, cutting them off from the border with Russia, which Kiev believes is the source of most of their arms and reinforcement.
Late Thursday, Ukrainian troops entered the town of Lysychansk, which has been in rebel hands for several months, the military press office said. Rebels on Friday morning admitted in comments reported by Interfax news agency that they had fled the town, which is about 50 miles northwest of the regional capital, Luhansk.
On Friday, Ukraine's parliament said it had yet to receive a resignation letter from Prime Minister Arseniy Yatsenyuk so it could not vote on whether to accept it or not, stalling work at the heart of government.
Yatsenyuk, Ukraine's point person for the West during much of Ukraine’s turmoil since November, had tendered his resignation Thursday, saying parliament was betraying its people's demands for change by failing to pass legislation.
The move could hamstring decision-making as Ukraine struggles to fund its offensive against the rebels, and deals with the aftermath of the Malaysian Airlines Flight 17 crash.
Al Jazeera and wire services