DAVYDO-MYKILSKE, Ukraine — Russia sent dozens of aid trucks into rebel-held eastern Ukraine on Friday without Kiev’s approval, saying its patience had worn out with the Ukrainian government’s stalling tactics. Ukraine called the move a “direct invasion.”

The unilateral move sharply raised the stakes in eastern Ukraine, for any attack on the convoy could draw the Russian military directly into the conflict between the Ukrainian government in Kiev and separatist rebels in the east. Ukraine has long accused Russia of supporting and arming the rebels, a charge Russia denies.

The white-tarped semis said to be carrying food, water, generators and sleeping bags are intended to help civilians in the city of Luhansk, where government forces are besieging pro-Russian separatists. The city only 20 kilometers (12 miles) from the Russian border has seen weeks of heavy shelling that has cut off power, water and phone lines and has left food supplies scarce.

In the past few days, Ukraine says its troops have recaptured significant parts of Luhansk, the second-largest rebel-held city, and suspicions are running high that Moscow’s humanitarian operation may instead be aimed at halting Kiev’s military momentum. Fierce fighting has been reported this week both around Luhansk and the largest rebel-held city, Donetsk, with dozens of casualties.

Four troops were killed and 23 wounded in the past 24 hours, the government reported at noon Friday.

The International Committee of the Red Cross, which had planned to escort the Russian aid convoy to assuage fears that it would be used as a cover for a Russian invasion, said it had not received enough security guarantees to do so Friday.

Ukrainian security service chief Valentyn Nalyvaichenko on Friday called the arrival of the convoy a “direct invasion.”

“This is a direct invasion done under the cover of the Red Cross for the first time ever,” Nalyvaichenko told reporters in the Ukrainian capital, Kiev. “These are military men who have been trained to carry cargo, trained to drive combat vehicles, tanks and artillery.”

He asserted that the half-empty aid trucks would be used to transport weapons to rebels and spirit away the bodies of Russian fighters killed in eastern Ukraine.

He promised, however, that Ukraine will not shell the convoy.

AP journalists heard the contents of many aid trucks rattling and sliding around on the country road, confirming that many vehicles were only partially loaded.

Ukraine had authorized the entrance of a few dozen trucks, but the number of Russian vehicles entering the country through a rebel-held border point Friday was clearly way beyond that amount.

An Associated Press reporter saw a priest blessing the first truck in the convoy at the rebel-held checkpoint and then climbing into the passenger seat. A rebel commander on the scene said 34 trucks had gone through. On the Russia side of the border, an Associated Press reporter saw an additional 32 trucks entering the customs control zone.

“The Russian side has decided to act,” said a statement on the Russian Foreign Ministry’s website. “Our column with humanitarian aid is starting to move in the direction of Luhansk.”

The Red Cross said in a statement on Twitter that it is not escorting the convoy due to security concerns, as shelling had continued overnight.

“We’ve not received sufficient security guarantees from the fighting parties,” it said.

A rebel commander on the scene who identified himself only by the codename Kot said the trucks were headed for Luhansk.

Shortly after leaving the rebel-held border town of Izvaryne, the convoy left the main road to Luhansk and headed north onto a country road, parking in the village of Uralo-Kavkaz, possibly to avoid areas controlled by Ukrainian troops.

The road on which the Russian trucks are traveling appears to be same one also being used by rebel forces. Around lunchtime, around 20 green military supply vehicles were seen traveling in the opposite direction to the convoy. Some were flatbed trucks, while others were fuel tankers. Other smaller rebel vehicles could be seen driving around.

Later, the convoy moved along winding village roads hugging the Russian border and made a wide loop to avoid the main highway to Luhansk. In the village of Davydo-Mykilske,  less than one kilometer (half a mile) west of the border, AP reporters saw three rebel tanks, dozens of militiamen and several armored personnel carriers.

The trucks from Moscow had been stranded in a customs zone for more than a week since reaching the border, as the two sides battled over where they should enter Ukraine. The Russian Foreign Ministry voiced increasing frustration at what it said were Kiev’s efforts to stall its delivery, while Ukraine demanded that the trucks enter through a government-controlled border post.

The Russian Foreign Ministry has accused the government in Kiev of shelling residential areas that the convoy would have to pass through, thereby making its onward travel impossible.

“There is increasingly a sense that the Ukrainian leaders are deliberately dragging out the delivery of the humanitarian load until there is a situation in which there will no longer be anyone left to help,” it said Friday in a statement.

Ukraine’s Foreign Ministry retorted with a statement accusing Russia of “ignoring international rules, procedures and agreements that have been reached” and moving the aid. The ministry said Ukrainian border guards were not allowed to inspect the remaining vehicles.

In response to the Russian aid convoy, Ukraine’s government mounted its own humanitarian supply earlier this week for those affected by fighting in the east. The rebels have said they will not allow that material to enter their territory.

The fighting in eastern Ukraine began in mid-April, a month after Russia annexed Ukraine’s southern Black Sea peninsula. It has killed over 2,000 people and forced 340,000 to flee, according to the United Nations.