Ukraine's military made advances in its fight against pro-Russian separatists Sunday, penetrating territory the separatists held in Donetsk and Luhansk in the eastern part of the country, government sources tell CNN.
Ukrainian government forces regained control over the strategic town of Yasynuvata, according to the official Twitter account of President Petro Poroshenko, and the army has entered Donetsk and raised the Ukrainian flag in front of the district's police offices, said National Defense and Security Council spokesman Col. Andriy Lysenko.
As fighting continues, Ukrainian officials acknowledged that a convoy of more than 260 Russian vehicles on the border is, in fact, carrying humanitarian aid, a statement on the Ukrainian Cabinet website said. The convoy initially sparked fears that Russia was trying to use a humanitarian convoy as a cover for sending in more aid and weapons for pro-Russian rebels in eastern Ukraine.
Thousands of people in that region have no access to water, electricity and proper medical aid, humanitarian agencies have said.
Delay in aid delivery likely
But there could be a hold up on the delivery of those items.
Ukraine received an inventory of the supplies Saturday, which had been signed by the head of the regional International Committee of the Red Cross delegation to Russia.
Pascal Cuttat says there are still "basic technical details" that need to be discussed.
The convoy's inspection will not happen Sunday, said Victoria Zotikova, a spokeswoman for the ICRC.
Zotikova added that the aid agency is missing security guarantees from all sides.
Moscow says the trucks contain grain, sugar, baby food, medical supplies and sleeping bags -- a claim that Kiev initially doubted.
The Ukrainian recognized governor of Luhansk, Irina Verigina, said this week that she doesn't want aid from Russia.
Ukraine says it is distributing its own aid through the Red Cross.
"They send us tanks and Grads (rocket-launching vehicles) overnight and offer to send humanitarian aid by day," Verigina said.
Ukraine: We destroyed most of a Russian convoy
Ukraine claims its artillery destroyed much of a military convoy that crossed from Russia into Ukraine last week, an incursion that two British newspaper journalists say they witnessed.
If true, Ukraine's account and the British reports appear to give credence to what Kiev has long alleged -- that Russia has been sending troops and arms into eastern Ukraine.
A diplomatic row was brewing Friday over the reports, with the United Kingdom's foreign office summoning Russia's ambassador in London to explain the incident.
Russia's foreign ministry has denied any such incursion, and its foreign minister will meet in Berlin with his counterparts from Ukraine, Germany and France on Sunday, state-run news agency RIA-Novosti reported. The meeting's agenda wasn't immediately released.
Those concerns took on a new light when British media outlets The Guardian and The Telegraph reported that armored personnel carriers, along with other vehicles with Russian military plates, crossed the border near Donetsk.
The Guardian reported that it witnessed 23 armored personnel carriers, in addition to other vehicles with Russian military plates, cross into Ukraine through a gap in a barbed wire fence. "Armed men were visible in the gloom by the border fence as the column moved into Ukraine," the Guardian report reads.
This is the first time foreign media recorded such an incursion, though it illustrates what Kiev has said has been happening for months -- that Russia has been sending troops and equipment to help the rebels, said Lysenko.
Poroshenko told British Prime Minister David Cameron that Ukrainian forces destroyed "the majority" of the Russian vehicles, Poroshenko's office said.
Poroshenko "expressed concern over the situation on the border, particularly over the fact that the inflow of Russian arms and military machines in Ukraine through the open part of the border continued," his office said.
Lysenko said he didn't know exactly how many vehicles crossed the border, or how many Ukraine's artillery managed to destroy.
Battle rages on
A Ukrainian fighter jet was shot down on Sunday in the Luhansk region, Leonid Matyuhin, the spokesman for Ukraine's counter-terrorist operation, told CNN. The pilot managed to eject and is safe, Ukrainian state media reported.
The ongoing fighting -- sparked last year with by political crisis over whether Ukraine would seek closer ties with Europe or Russia -- has left more than 2,000 people dead and just under 5,000 wounded in eastern Ukraine since mid-April, according to estimates from U.N. officials.
The United States and the European Union have applied steadily increasing sanctions against Russian officials, banks and other interests since March, when Russia annexed the Black Sea Ukrainian peninsula of Crimea. Russia's move came a month after Ukraine's parliament ousted pro-Moscow President Viktor Yanukovych.
left office after violent protests against his government in the capital, Kiev. Those protests were motivated in part by his decision to back out of a trade deal with the European Union in favor of closer ties with Russia.