Separatists killed 23 Ukrainian soldiers and wounded 93 in fighting near the border with Russia as the European Union added 11 names to a list of people it has sanctioned for supporting the insurrection.

Some of the soldiers died after being hit by fire from Grad rocket systems near Zelenopillya, a village about 5 kilometers (3 miles) from Ukraine’s eastern frontier, military spokesman Vladyslav Seleznyov said by phone. A day earlier, the ministry said Ukrainian forces killed more than 50 insurgents in air strikes near Donetsk, the country’s largest eastern city.

“In the past 24 hours in different areas, 23 Ukrainian troops were killed,” Seleznyov said today. “Ninety-three were wounded among Ukraine’s military and border service. The wounds include shell shock.”

The government is trying to tighten an encirclement around the militants after forcing them to retreat from their former strongholds of Slovyansk and Kramatorsk last week. The rebels are now preparing for a siege in Donetsk, where they said they may have to evacuate 100,000 civilians, and have also continued to attack Ukrainian forces across the region in the country’s bloodiest conflict since World War II.

EU governments imposed asset freezes and travel bans on 11 more people accused of fomenting unrest and will publish the names tomorrow, the 28-nation bloc said in a statement in Brussels. Most of the new targets are separatists, an EU official said before the announcement. The EU has blacklisted 72 people and two companies connected with the destabilization of Ukraine and Russia’s annexation of Crimea in March.

The EU’s first opportunity to consider wider penalties on Russian industry, investment or trade will be at a July 16 summit. Objections by countries such as Italy, Austria, Slovakia, France and Greece have frustrated moves toward broader sanctions, which require unanimity.

“We have to be very cautious,” Hungarian Foreign Minister Tibor Navracsics said in an interview in Dubrovnik, Croatia today. “It’s not clear whether the fighters are separatists with no Russian help or there are paramilitaries with some Russian support. The answer to that question is crucial in deciding the third round of the sanctions.”

Ukrainian President Petro Poroshenko told German Chancellor Angela Merkel and U.S. Vice President Joe Biden by phone last night that he was ready for truce talks if a cease-fire monitoring system can be put in place and weapons and fighters stop flowing over the border from Russia, his office said in a statement today.

Poroshenko dismissed Russia’s declaration that the separatists want peace talks, while Russian Foreign Minister Sergei Lavrov has said the militias are ready and “ultimatums and pre-conditions” must not stand in the way.

Earlier, Merkel and French President Francois Hollande told Russian President Vladimir Putin that Russia should use its influence to facilitate an immediate meeting between the separatists and representatives of Ukraine and the OSCE, according to a German government statement. The leaders agreed a cease-fire is the highest priority.

“We need concrete proof that Russia is really engaged in de-escalation, as we still see military support by Russia and separatists using military weapons of Russian origin,” Titus Corlatean, foreign minister of EU member Romania, said in an interview in Dubrovnik, Croatia.

About 20 Russian tanks crossed the Ukrainian border in the Luhansk region from Russia today, Ukrainian Channel 5 reported, citing local residents. Putin’s government has denied the charges that it’s supporting the rebels.

Separatists attacked the airport at Donetsk overnight, according to Ukrainian officials. The rebels are preparing for a siege of the city by government troops and may evacuate about 100,000 civilians from the area, Interfax news service reported yesterday, citing Alexander Borodai, the prime minister of the self-proclaimed Donetsk People’s Republic.

Violence continued to take a toll on the region’s inhabitants, hundreds of whom have died in the fighting. A mortar round hit a bus carrying workers from DTEK, a coal-mining and power producing company owned by Ukraine’s richest man Rinat Akhmetov, killing four, according to Interfax.

DTEK said it had suspended operation in some facilities because of the violence, according to a statement, while Cargill Inc. halted work at a sunflower-oil plant in the Donetsk region on July 4 and said it was occupied by gunmen.

The government in Kiev said one of its military officers was captured by separatists last month and taken illegally across the border. Russia denied snatching the female pilot, who it alleges was involved in the death of two Russian reporters.

Russia also said yesterday its neighbor fired on a border post, while Ukraine said it was the separatists who were firing on Russian territory to discredit the army and accused Russia of massing forces on the frontier.