At least 474 civilians, including 29 children, have been killed in Ukraine since Russia attacked the country almost two weeks ago, the United Nations' human rights office said Tuesday.

"Real toll is much higher," the Office of the U.N. High Commissioner for Human Rights in Ukraine said. The 474 deaths are just those recorded, and many reports are delayed or pending further corroboration, it said.

The U.N. office said 861 civilians have been reported wounded. Most of the casualties are from explosives affecting large areas like artillery and airstrikes, it said. 

More than 2 million refugees have fled Ukraine since Russia attacked and invaded Feb. 24, the U.N. refugee agency has said.

Dotdash Meredith, the media company that owns publications such as People magazine and Entertainment Weekly, told NBC News on Tuesday that it is cutting off business in Russia.

"We had very limited business operations in Russia and those relationships have been, or are in the process of being, terminated," a Dotdash Meredith spokesperson said.

The statement comes the same day Condé Nast, the publishing giant behind Vogue, Vanity Fair and The New Yorker, announced it was suspending business operations in Russia.

“We continue to be shocked and horrified by the senseless violence and tragic humanitarian crisis in Ukraine,” CEO Roger Lynch said in a memo to Condé Nast’s global employees, according to Vogue Business.

"With journalists and editorial teams around the world, it is paramount that we are able to produce our content without risk to our staff’s security and safety. Recently, the Russian government passed new censorship laws that now make it impossible for us to do so," Lynch added.

The moves are part of a wider corporate backlash against Russian President Vladimir Putin's invasion of Ukraine. World-famous brands such as McDonald's and Coca-Cola have bowed to pressure to halt business in Russia.

U.S. officials expressed doubts Tuesday about Poland's plan to transfer MiG-29 jets to the U.S. amid Russia's invasion and war against Ukraine.

Poland had announced earlier that it was ready to send its MiG fighters to Ramstein Air Base, Germany, "and place them at the disposal of the Government of the United States of America."

Secretary of State Antony Blinken has said the U.S. would give a "green light" if Poland or another NATO member were to send jets to Ukraine. A U.S. official said the U.S. position was in support of Poland's sending the jets directly to Ukraine, not for the U.S. to act as an intermediary.

Defense Department press secretary John Kirby also expressed doubts.

"The prospect of fighter jets ‘at the disposal of the Government of the United States of America’ departing from a U.S./NATO base in Germany to fly into airspace that is contested with Russia over Ukraine raises serious concerns for the entire NATO alliance," Kirby said in a statement.

He said discussions would continue, but "we do not believe Poland’s proposal is a tenable one." 

Ukrainian President Volodymyr Zelenskyy thanked Joe Biden on Tuesday for a ban on Russian energy products, calling the decision a “step that will significantly weaken the occupiers” and “make them pay” for their aggression.

“I am personally thankful to the United States President Biden for this decision, for this leadership, for this strong signal to the rest of the world,” he said in a video posted on Telegram, according to an NBC News translation.

“Every cent paid to Russia they turn into bullets and missiles that are aimed at other sovereign states," he said. "Either Russia respects international law and does not engage in war, or it will have no money to start wars.”

Biden’s decision, which aims to ramp up pressure on Russia’s oil-dependent economy and takes effect immediately, blocks all new oil and gas contracts. A 45-day wind-down period was provided for existing contracts.

Russian oil accounts for just under 10 percent of all U.S. oil imports. 

Zelenskyy also thanked U.K. Prime Minister Boris Johnson for a ban on oil Russian products that was also announced Tuesday. Johnson said the U.K., which gets 8 percent of its oil and 4 percent of its gas from Russia, will phase out imports by the end of the year. 

Officials in the European Union, where Russian oil accounts for one-third of the region’s imports, said Tuesday that they want to reduce Russian oil imports by two-thirds by the end of the year and halt all oil purchases by the end of the decade.

Zelenskyy said he was “expecting tough decisions” from the 27-member bloc in the form of additional sanctions against the architects of the invasion of his country.

Fitch on Tuesday downgraded Russia's sovereign rating by six notches further into the junk territory from "B" to "C," saying a default is imminent as sanctions and trade restrictions have undermined its willingness to service debt.

Western sanctions have thrown Russia's financial markets into turmoil after it invaded Ukraine, raising significant concerns over its ability and willingness to service debt.

Fitch pointed to a presidential decree that could force a redenomination of foreign-currency sovereign debt payments into local currency for creditors in specified countries.

"‍Further ratcheting up of sanctions and proposals that could limit trade in energy increase probability of a policy response by Russia that includes at least selective non-payment of its sovereign debt obligations," the ratings agency said in a statement.

On March 16, Russia is due to pay $107 million in coupons across two bonds, though it has a 30-day grace period to make the payments.

The "C" rating in Fitch's assessment is only one step above default, bringing it in line with the Moody's current equivalent score of "Ca."

The change comes less than a week after Fitch revoked Russia's investment-grade status, slashing its rating to "B" from "BBB." Peers Moody's and S&P had also lowered their sovereign ratings. 

Biden didn't race to ban Russian oil. He was pushed to do it by an unusual alliance of Republicans and climate-conscious liberals.

Of course, supporters of the embargo uniformly cite the defense of innocent Ukrainians as their top priority. But that's not the whole story.

Read the full story here.

Coca-Cola announced Tuesday it was suspending its business in Russia, while Pepsico said it was halting beverage sales.

The companies — the targets of calls for a boycott on social media in recent days — employ tens of thousands of people in Russia, which has already been hit hard by international financial sanctions. 

In a memo to employees obtained by CNBC, CEO Ramon Laguarta said Pepsico was suspending the sale of its soft drinks in the country but would continue manufacturing some other goods there. Laguarta said the company has "a responsibility to continue to offer our other products in Russia, including daily essentials such as milk and other dairy offerings, baby formula and baby food. By continuing to operate, we will also continue to support the livelihoods of our 20,000 Russian associates and the 40,000 Russian agricultural workers in our supply chain as they face significant challenges and uncertainty ahead."

The Coca-Cola Co. said in a terse statement "that it is suspending its business in Russia" without elaborating on the details. 

"Our hearts are with the people who are enduring unconscionable effects from these tragic events in Ukraine," the statement said. "We will continue to monitor and assess the situation as circumstances evolve."

Coke owns 10 plants and employs thousands of people across Russia, the Russian state news agency Tass reported last week.