Ukraine has accused a brigade of the Russian Ground Forces of committing war crimes in the Ukrainian city of Bucha, northwest of Kyiv.

The Main Directorate of Intelligence of the Ukrainian Ministry of Defense published online Monday what it said was a list with the names of hundreds of personnel of Russia's 64th Motor Rifle Brigade whom they believe were directly responsible for atrocities in Bucha. Ukrainian officials have said there is evidence of other Russian units being involved.

Ukrainian authorities announced Sunday that 410 civilians were found dead in recently recaptured towns near the capital as part of an investigation into possible war crimes by Russian forces. Images emerged showing bodies, some of which showed signs of torture, in civilian clothes strewn in streets and in mass graves across Bucha, northwest of Kyiv. ABC News journalists on the ground saw some of the dead, including a family that locals said were executed with their hands bound.

Russia has denied the claims.

-ABC News' Natalia Kushnir and Fidel Pavlenko

A $90 million yacht that belongs to Russian oligarch Viktor Vekselberg was seized Monday in Marina Real in the Spanish port of Palma de Mallorca, two U.S. law enforcement sources told ABC News.

The 255-foot yacht was seized by Spanish authorities and KleptoCapture, the U.S. Department of Justice task force charged with finding assets of oligarchs trying to evade sanctions over Russia’s invasion of Ukraine.

Vekselberg was among the oligarchs sanctioned previously by the United States in 2018 after Russia invaded Crimea.

The task force is trying to find yachts, airplanes and other moveable properties before the oligarchs can move them to jurisdictions where it might be more difficult for U.S. authorities to investigate.

"Today marks our taskforce’s first seizure of an asset belonging to a sanctioned individual with close ties to the Russian regime. It will not be the last," U.S. Attorney General Merrick Garland said in a statement. "Together, with our international partners, we will do everything possible to hold accountable any individual whose criminal acts enable the Russian government to continue its unjust war."

-ABC News' Luke Barr and Aaron Katersky

Russian Foreign Minister Sergei Lavrov has accused Ukrainian forces of staging an attack in Bucha, northwest of Kyiv, where images have emerged showing bodies in civilian clothes lying in the streets and in mass graves.

"The other day, another fake attack was launched in the city of Bucha, Kyiv region, after Russian military personnel left from there in accordance with the plans and agreements reached," Lavrov told reporters in Moscow on Monday. "A few days later, a staging was arranged there, which was dispersed through all channels and social networks by Ukrainian representatives and their Western patrons."

According to Lavrov, Russian forces vacated the area on March 30.

“On March 31, the mayor [of Bucha] solemnly said that everything was fine there," he added. "And two days later, we saw how the same production was organized on the streets, which they are now trying to use for anti-Russian purposes."

Ukrainian Prosecutor General Iryna Venedyktova announced Sunday that 410 civilians were found dead in recently recaptured towns near the capital as part of an investigation into possible war crimes by Russian forces. Some photos taken Sunday in Bucha show unarmed individuals who appear to have been executed with their hands or legs bound. A number of world leaders have accused Russia of committing the atrocities.

Russia responded on Monday to accusations that its troops have deliberately killed civilians in Ukraine, after images emerged showing bodies in civilian clothes scattered in areas on the outskirts of the capital that were recently recaptured from Russian forces.

Ukrainian Prosecutor General Iryna Venedyktova said Sunday that 410 civilians were found dead in towns near Kyiv. Associated Press journalists reported seeing 21 bodies in various spots around Bucha, northwest of the capital, many of whom appeared to have been shot at close range and showed signs of torture, including some who had their hands tied behind their backs.

During a daily press briefing on Monday, Kremlin spokesman Dmitry Peskov said Russia "categorically dismiss[es] any accusations" of its role in civilian killings and that Moscow does not trust the evidence in Bucha.

"This information should be seriously doubted," Peskov told reporters. "From what we have seen, the video materials cannot be trusted to a large extent, as our specialists from the Defense Ministry have detected signs of video forgery and other kinds of fakes."

The Kremlin demands that "international leaders do not jump to conclusions, do not make hasty unsupported accusations but at least seek information from various sources and at least listen to our arguments," Peskov said.

"The facts, the chronology of events also do not speak in favor of the credibility of these claims," he added.

Russia will reiterate its calls to discuss the matter at the United Nations Security Council on Monday, according to Peskov.

"We believe that the issue should be discussed at the highest level, so we have proposed that it be discussed at the Security Council. We are aware that the initiative has been blocked," he said. "Our diplomats will continue active efforts towards putting this item on the Security Council's agenda. This issue is too serious."

"The initiative aimed to put the item on the Security Council agenda demonstrates that Russia wants and actually demands its discussion at the international level," he added.

All Russian troops have left the Ukrainian cities of Kyiv and Chernihiv, withdrawing north toward the borders of Belarus and Russia to consolidate before likely redeploying to the Donbas region in eastern Ukraine, a senior U.S. defense official told reporters Wednesday.

But even with the Russians gone, the territory remains treacherous.

"There are some indications that they left behind mines and things like that, so the Ukrainians are being somewhat careful in some areas north of Kyiv as they begin to clear the ground and clear the territory and re-occupy it," the official said.

While the U.S. hasn't yet seen these troops redeploy elsewhere in Ukraine, it'll likely happen soon, according to the official. Ukrainian forces are preparing for a major fight in Donbas, the official said.

The official also said the Pentagon is "monitoring" an apparent nitric acid explosion in Ukraine's Luhansk region, which Russia blamed on Ukraine.

"We've seen the Russians claim that this was a Ukrainian attack on this. We do not believe that is true," the official said. "We do believe that the Russians are responsible, but exactly what they used when they did it, why they did it, what the damage is, we just don't have that level of detail," the official said.

The official also noted that a small number of Ukrainians currently in the U.S. for "professional military education" were pulled aside for a couple days of training on Switchblade drones, which the U.S. is sending overseas as part of its military aid, according to the official.

"Although it's not a very difficult system to operate, we took advantage of having them in the country to give them some rudimentary training on that," the official said.

-ABC News' Matt Seyler