KIEV — Fighting in eastern Ukraine killed at least nine Ukrainian soldiers Friday as government troops, using heavy artillery and combat jets, pressed their offensive against pro-Russia insurgents.
Prospects of a truce appeared dim. Ukraine’s president, Petro Poroshenko, said his country is ready to conduct another round of talks between representatives from Ukraine, Russia, and the rebels on Saturday but did not name the location.
Two previous rounds of such negotiations held during a 10-day cease-fire yielded no visible progress, but they brought the warring parties together for the first time.
Moscow strongly pushed for reestablishing the truce and holding more talks in an apparent hope to negotiate a settlement that would allow it to secure a degree of influence over the neighbor.
The fighting is putting more pressure on President Vladimir Putin of Russia, who has been facing increasingly angry nationalist demands to send troops to help the insurgency, a move that would inevitably trigger more sanctions.
Ukraine’s National Security Council chief, Andriy Parubiy, said Friday that Russia was massing troops near the Ukrainian border and claimed that it let insurgents attack border posts from its side. The statements could not be independently verified.
The two neighbors, who share a 1,250-mile border that is unmarked and unguarded other than a few checkpoints, have been trading claims since Ukraine began fighting pro-Russia separatists in April.
The government said nine troops were killed and 13 others were wounded in Friday’s fighting in the east, according to the Interfax news agency. It did not elaborate on where or how the deaths occurred.
Valentyn Nalyvaychenko, the head of Ukraine’s SBU security service, told journalists that over the past four days 20 Russian tanks or armored vehicles had illegally crossed the border to take part in the insurgency.
Ukraine says Russia is arming and supporting the separatists, a charge that Russia denies. For its part, Moscow has repeatedly accused Ukrainian troops of firing shells that landed in Russia and on one occasion last month hit a Russian border post, wounding a customs officer.
Russian border guards said 10 artillery shells flew from the Ukrainian side Friday, but no one was injured.
It is nearly impossible to prove or dispel the claims from the opposing sides, since the fighting consists of intermittent clashes between small units with no fixed front line.
Five journalists have been killed covering the conflict and several teams of observers from the Organization for Security and Cooperation in Europe have been kidnapped by rebels.
Russia has proposed hosting both OSCE observers and Ukrainian officers at its border checkpoints to prove it is not fueling the mutiny.
The Russian Foreign Ministry accused Poroshenko’s government on Friday of dragging its feet on holding another round of negotiations to resume a truce and accused it of using cluster munitions against civilians.
Parubiy said government forces were attacking rebel positions in eastern Ukraine with artillery and planes and that 17 villages had been recaptured since a unilateral cease-fire expired Monday. He said Ukrainian forces control 23 of the 36 local regions within the Donetsk and Luhansk provinces that have declared independence.
Andrei Purgin of the separatist Donetsk People’s Republic dismissed the government’s report.
‘‘Maybe they occupied 17 villages of some sort, but there wasn’t a single militia fighter there,’’ he said.
Insurgents in Luhansk said Friday they have killed 125 Ukrainian troops, destroyed nine armored vehicles, and downed three combat aircraft since Wednesday.
Both sides’ claims of enemy losses have proven to be exaggerated in the past, however.
Friday’s fighting centered on the outskirts of Slovyansk, a city in the Donetsk region that has been a key flashpoint in the fighting. The military reported to Poroshenko that they flushed the insurgents out of Mykolaivka on the outskirts of Slovyansk, capturing 50 of them.
Rebels also shelled Donetsk’s airport overnight, leaving parts burning Friday.
The mutiny in eastern Ukraine, which erupted in mid-April after the ouster of the nation’s pro-Moscow president and the subsequent Russia’s annexation of Crimea, has killed more than 400 people, according to the United Nations.