A rocket attack by pro-Russian rebels on a post on Ukraine's border with Russia on Friday killed at least 19 government servicemen and wounded 93 others, Ukraine's Defense Ministry said, promising swift retribution from Kyiv.
Zoryan Shkyryak, an adviser to Ukrainian Interior Minister Arseny Avakov, told reporters in Kyiv that rebel forces fired Grad missiles at Ukrainian troops located in the village of Zelenopillya in the Luhansk region.
President Petro Poroshenko called an emergency meeting to discuss what could be the deadliest rebel attack on government forces since the Ukrainian military ended a unilateral cease-fire June 30. He said those responsible for the attack would be "found and destroyed," adding that for every Ukrainian soldier killed, the rebels would pay with "dozens and hundreds of their own."
Kyiv, which has been trying to take greater control of its border with Russia, blames Moscow for fanning the violence and letting fighters and high-powered weaponry cross the frontier from Russia to Ukraine.
The attack comes after government forces appeared to be gaining the upper hand in a three-month battle with separatists, who have set up “people's republics” in the Russian-speaking east of the country and said they want to join Russia.
Last week, Ukrainian forces drove the rebels out of several cities, including Slovyansk, which was their main stronghold. The separatists have massed in Donetsk, the region's industrial hub, with a population of 900,000. Poroshenko's government has threatened a “nasty surprise” to chase them out while limiting civilian casualties.
On Thursday, the government said security forces had seized a border checkpoint in the Luhansk region and regained control of the town of Siversk, 70 kilometers, or 43 miles, northwest of Luhansk city.
Separatists confirmed Ukraine’s control of Siversk, saying they retreated toward Donetsk to avoid being encircled by Ukrainian troops.
Human rights violations reported
Meanwhile, Amnesty International says it has "graphic and compelling evidence" of beatings and torture in eastern Ukraine, with armed pro-Russian separatists responsible for most of the violence.
In a new report, the rights group says victims are "often subjected to stomach-turning beatings and torture." It also says there is evidence of a smaller number of abuses by pro-Kyiv forces.
The report says the United Nations Human Rights Monitoring Mission for Ukraine has recorded 222 abductions since April, when separatists seeking autonomy in the east launched their rebellion against the Kyiv government.
People trying to flee
Donesk's main railway station station was crowded with people trying to flee the city, fearing the kind of damage Slovyansk experienced as Ukraine's government fought to wrest control. Reuters news service said some people reported waiting in ticket lines for two hours.
Some 70,000 residents already had fled, separatist leader Alexander Borodai told journalists Thursday, Reuters reported.
Elsewhere in the Luhansk region, four servicemen were killed when their armored personnel vehicle detonated a mine, said military spokesman Andriy Lysenko.
Another military spokesman said a soldier was also killed in the town of Karlovka in Donetsk province.
Separately, at least five miners died and another five were injured when their bus came under fire from the rebels, Lysenko said.
The bus shelling forced energy and coal company DTEK, which employed the miners, to suspend operations at four mines that employ 4,500 people in the economically depressed industrial province of Luhansk, Interfax news agency quoted the company's general director as saying.
In diplomatic attempts to end the worst crisis between Russia and the West since the Cold War, the White House said Poroshenko told U.S. Vice President Joe Biden that Russia and Ukrainian separatists had refused multiple proposals by Kyiv for venues to negotiate a ceasefire.
Speaking to Russian President Vladimir Putin on Thursday, French President Francois Hollande and Merkel urged Moscow to exert pressure on the separatists to de-escalate the violence.
German Chancellor Angela Merkel urged Poroshenko by telephone on Thursday to be strategic in battling pro-Russian rebels and to safeguard the general population, a German government spokesman said.
“The chancellor urged President Poroshenko to maintain a sense of proportion in his legitimate actions against the separatists and to protect the civilian population,” German government spokesman Steffen Seibert said.
Both agreed on the need for a meeting of the contact group that helped smooth the way for Poroshenko's recent 10-day cease-fire, the statement said.
The chance for peace talks withered after Poroshenko called off the cease-fire June 30 after rebels repeatedly violated it, infuriating many Ukrainians.
Some information for this report was contributed by Reuters.