Russia has been accused of weaponising food as it blocks crucial grain exports from Ukraine which could lead to the starvation of millions of people around the world, including Africa.

US Secretary of State Antony Blinken said not only was Russia using food to break the spirit of the Ukrainian people, it was also blocking exports of vital crops.

It comes as the World Food Program warned Russia’s failure to open closed ports in Ukraine would bring millions of people to the brink of starvation.

Ukraine is one of the world’s biggest exporters of corn, wheat and sunflower oil which have been largely blocked during the war.

Mr Blinken has placed the blame for food shortages being experienced around the world on Russia and warned the situation could worsen.

“The Russian Federation claims falsely that the international community’s sanctions are to blame for worsening the global food crisis,” he said.

“Sanctions aren’t blocking Black Sea ports, trapping ships filled with food, and destroying Ukrainian roads and railways — Russia is.”

Mr Blinken called on Russia to stop blockading ports in the Black Sea and the sea of Azov and “allow for the free flow of ships and trains and trucks carrying food out of Ukraine”.

“Stop preventing food and other life-saving supplies from reaching civilians in besieged Ukrainian towns and cities; stop threatening to withhold food and fertiliser exports from countries that criticise your war of aggression,” Mr Blinken said.

However The Kremlin’s foreign ministry has called for international sanctions against Russia to be lifted before it would consider allowing access to Ukraine’s ports.

Ukraine’s Foreign Minister Dmytro Kuleba said Ukraine was seeking ways to “hold Russia accountable for its aggression and unblock Ukraine’s food exports”.

“Russia bears full responsibility not only for killing, torturing, and raping Ukrainians, but also for starving people across the world, including in Africa,” Mr Kuleba tweeted.

Meanwhile US President Joe Biden has given his strong support to Finland and Sweden joining NATO on what he said was a “momentous day” after meeting the countries’ two leaders.

Mr Biden discussed the NATO applications with Swedish Prime Minister Magdalena Andersson and Finnish President Sauli Niinistö at the White House.

Sweden and Finland are setting aside their long-standing neutrality in their move to join the security alliance in response to Russia’s invasion of Ukraine.

Mr Biden has made uniting Europe against Russia’s invasion of Ukraine a top priority. Finland shares an 1800km border with Russia and had not previously joined NATO so as not to antagonise its neighbour.

NATO Secretary General Jens Stoltenberg said he was confident NATO’s 30 members would make a quick decision to welcome them.

However Turkey has raised questions about including them, asking Sweden to halt support for Kurdish militants it considers a terrorist group and both to lift their bans on some sales of arms to Turkey.

All 30 NATO members need to approve any new entrant.

Mr Biden’s meeting comes as the US Congress approved for $US40 billion in aid for Ukraine to provide weapons and humanitarian assistance through September — the largest package since the invasion.

Laser weapons mocked

Volodymyr Zelensky has mocked Russia’s claim that it has shot laser beams on the battlefield to zap a Ukrainian drone in seconds, with the US saying there is no evidence of the new weapons.

Mr Zelensky labelled the enemy’s laser weapons as propaganda and compared it to Nazi Germany’s so-called “wonder weapons” in World War II.

“The clearer it became that they had no chance in the war, the more propaganda there was about an amazing weapon that would be so powerful as to ensure a turning point,” Mr Zelensky said in a video address.

“And so we see that in the third month of a full-scale war, Russia is trying to find its ‘wonder weapon’… this all clearly shows the complete failure of the mission.”

Russia’s deputy prime minister in charge of military development Yury Borisov said on TV that a laser prototype called Zadira had burned up a Ukrainian drone within five seconds from 5km away.

He also claimed Russia was using its previous laser technology called Peresvet which could interfere with satellites.

“If Peresvet blinds, then the new generation of laser weapons lead to the physical destruction of the target — thermal destruction, they burn up,” Mr Borisov said.

-with AAP