KYIV, FEBRUARY 1

Ukraine claimed Thursday it used sea drones to sink a Russian corvette in the Black Sea as Russian investigators alleged that a Russian military transport plane that crashed last month was brought down by two US-made Patriot missiles fired by Kyiv's forces.

Ukraine's military intelligence agency, known by its Ukrainian acronym GUR, published a video it said showed naval drones assaulting the Russian missile-armed cutter Ivanovets on Wednesday night.

The footage released on GUR's social media purports to show multiple naval drones crashing into a vessel and exploding. According to GUR, the ship costing between $60-$70 million was on patrol on Lake Donuzlav in western Crimea, when a GUR special unit struck it. The lake has been more of a bay since 1961, when a channel connecting it to the Black Sea was dug out.

Disinformation has been part of the grinding war, which marks its second anniversary on Feb. 24, and it was not possible to independently verify either side's claims.

The private security firm Ambrey said Ukraine used up to six sea drones, each of which usually carry 300 kilograms (661 pounds) of explosives, in the attack. The GUR footage showed the ship was sinking.

Russian officials made no immediate comment on the Ivanovets.

A Western official backed the Ukrainian account, saying it was 'highly likely that uncrewed surface vessels were responsible for the strike on the Ivanovets.' The official spoke on condition of anonymity to discuss intelligence.

Ukrainian attacks on Russian aircraft and ships in the Black Sea have helped push Moscow's naval forces back, allowing Kyiv to increase crucial exports of grain and other goods through its southern ports.

Ambrey, the security company, noted that any unexploded drones could be a threat for Black Sea shipping.

Meanwhile, Russia's Investigative Committee, the main state criminal investigation agency, said Thursday it deduced that the Russian Il-76 military transport plane that crashed near the border with Ukraine on Jan. 24 was downed using the U.S.-made Patriot air defense system, which Western allies have supplied to Kyiv.

Russian officials claimed there were 74 people on board, including 65 Ukrainian prisoners of war, six crew members and three Russian servicemen. All were reported killed.

The two missiles were fired by the Ukrainian military from near the village of Lyptsi in the Kharkiv region of Ukraine, it said.

The committee said in a statement that 116 fragments of two MIM-104A missiles that were fired from the Patriot system were found near the crash site in the Belgorod region. It produced no physical evidence for its claims.

Meanwhile, along the front line stretching across eastern and southern Ukraine, the fighting continued to claim civilian casualties.

In the eastern Donetsk region, the Russian army shelled 11 towns and villages, killing one person in the village of Tsukuryne on Thursday. In Toretsk, two people were wounded during a rocket attack, the Ukrainian presidential office said.

In the south, six civilians were wounded in the Kherson region, including a husband and wife in Beryslav who were hit by a drone attack while riding a motorcycle through the city.