(USA TODAY) -- Ukrainian officials said Monday their troops are battling a convoy of Russian military vehicles that crossed the southeast border from Russia disguised as rebels, opening up a new war front in the southeast.
They said the column was en route to the city of Mariupol, a key government city on the Sea of Azov, but had been halted by Ukrainian troops near the town of Novoazovsk.
The purported incursion comes one day before Russian President Vladimir Putin and Ukrainian President Petro Poroshenko are scheduled to meet on the sidelines of a regional economic summit in Minsk to discuss the instability in Ukraine.
In Moscow, Russian Foreign Minister Sergei Lavrov said he not heard the reports of new military action in Ukraine but complained of regular "disinformation about our 'incursions.'"
Andriy Lysenko, a spokesman for Ukraine's National Security Council, told reporters that the column of 10 tanks, two armored vehicles and two trucks crossed the border near Shcherbak and that the nearby city of Novoazovsk was shelled during the night from Russia. He said they were Russian military vehicles bearing the flags of the separatist Donetsk rebels.
Lysenko said Mariupol has enough defenders "to repel any attack of uninvited guests." He said the 18-miles stretch of coastline road between Novoazovsk and Mariupol was under the Ukrainian control.
Ihor Mosiychuk, the deputy commander of the Ukrainian Azov battalion, said on Facebook on Monday that the convoy was made up of 30 tanks with symbols of the self-proclaimed Donetsk People's Republic, according to Interfax Ukraine.
On his web site, according to Ukrinform, the Ukrainian news agency, Mosiychuk called the action a"full-scale invasion!" Ukrainian officials stopped short of characterizing the action as an outright- invasion.
Until now, most of the fighting has taken place in eastern Ukraine, around the cities of Donetsk and Luhansk.
More than 2,000 people have died in clashes between Ukrainian troops and separatists since April. Russia has insisted that the rights of the largely ethnic Russians in the eastern regions of Ukraine be protected.
In Moscow, meanwhile, Lavrov also said that Russia hopes to send a second humanitarian convoy to southeastern Ukraine this week. Last week's convoy of around 280 trucks became a diplomatic tug-of-war between Russia and Ukraine, with the vehicles sitting at the border for over a week.
Ukraine said Russia would not comply with an agreement to open all vehicles to inspection and turn over the humanitarian effort to the International committee of the Red Cross. The ICRC said it did not join the convoy because of security concerns. Russia accused Ukraine of creating unnecessary delays.
Ukraine has accused Russia of using the convoys as a cover for aiding Russian-backed rebels in eastern Ukraine or as a pretext for a full-scale invasion.
The first convoy of trucks eventually crossed into Ukraine unauthorized, prompting condemnation from Ukraine, NATO, and the U.S. The trucks took their cargo to the besieged city of Luhansk and crossed back into Russia within 24 hours.
Contributing: Associated Press