Russia has seized large parts of Ukraine's coast, blocking farm exports and driving up the cost of grain.

Zelensky said Ukraine was now unable to export large amounts of wheat, corn, vegetable oil and other products that had played a "stabilising role in the global market".

"Millions of people may starve if the Russian blockade of the Black Sea continues," he said in a video statement to the TIME100 Gala 2022 in New York that was released by Ukrainian authorities on Thursday.

Ukraine and the West accuse Moscow of weaponising food supplies. Russia says Ukrainian mines laid at sea and international sanctions on Moscow are to blame.

Kyiv used to export most of its goods through seaports but since Russia's Feb. 24 invasion has been forced to transport grain by train via Ukraine's western border or via small Danube river ports.

Zelensky, who was included on Time magazine's list of the 100 most influential people of 2022, said he was grateful to US President Joe Biden for "uniting the free world when the Russian threat arose".

He also appealed to Ukraine's allies to supply it with more arms, drawing comparisons between what he described as Russian hatred and COVID-19.

"Weapons and sanctions are also a vaccine: a vaccine against COVID-22 brought by Russia. Hatred is a virus, and it’s even more deadly than COVID-19," he said.

Russia did not immediately respond to Zelensky's comments. Moscow says its "special military operation" in Ukraine is intended to disarm and "denazify" its neighbour. Ukraine and its allies say Moscow has launched an unprovoked war of aggression.

Meanwhile, UN chief Antonio Guterres said Wednesday that the consequences for the world of Russia's invasion of Ukraine are worsening, with 1.6 billion people likely to be affect.

"The war's impact on food security, energy and finance is systemic, severe, and speeding up," the Secretary-General said, presenting the UN's second report into the repercussions of the conflict.

He added that "for people around the world, the war is threatening to unleash an unprecedented wave of hunger and destitution, leaving social and economic chaos in its wake."

Guterres said that while this year's food crisis is "about lack of access," next year's "could be about lack of food."

"There is only one way to stop this gathering storm: the Russian invasion of Ukraine must end," he pleaded in a speech.

The head of the world body said he had asked colleagues to help find "a package deal that allows for the safe and secure export of Ukrainian-produced food through the Black Sea, and unimpeded access to global markets for Russian food and fertilizers."

"This deal is essential for hundreds of millions of people in developing countries, including in sub-Saharan Africa," said Guterres, quoted by AFP.

The UN report, led by diplomat Rebeca Grynspan, says that an estimated 94 countries, home to around 1.6 billion people, are "severely exposed to at least one dimension of the crisis and unable to cope with it."

"Out of the 1.6 billion, 1.2 billion or three quarters live in 'perfect-storm' countries that are severely exposed and vulnerable to all three dimensions of finance, food, and energy, simultaneously," it adds.

The report says that the war may increase the number of food-insecure people by 47 million people in 2022, bringing it to 323 million by the end of the year.

It is estimated that up to 58 million more Africans may fall into poverty this year, the document adds.

Extreme poverty in the Middle East and North Africa could increase by 2.8 million people in 2022, while in South Asia 500 million people are at risk, according to the report.

"Concrete efforts should be made to ensure critical supplies of food and energy reach the most vulnerable," the report says.