Boris Johnson has committed to working with Western allies to break the Russian “despicable blockade” on Ukrainian ports, in an effort to "avert a global food crisis”. 

The Prime Minister spoke to Ukrainian President Volodymyr Zelensky on Saturday morning about international efforts to put a stop to the blockade of major southern port Odesa on the Black Sea. 

Supplies of food and grain from Ukraine have been stopped since Vladimir Putin’s forces invaded, as the Russian navy blockades Odesa.

Millions of metric tons of grain are sitting in silos in the port city and other Ukrainian ports on the Black Sea. 

As the "bread basked of Europe", Ukraine was one of the world’s largest exporters of wheat, corn and sunflower oil.

The Russian invasion and Moscow’s mining of the access to the southern ports has halted much of that flow, endangering world food supplies.

Giving details of the phone call, a No 10 spokeswoman said: “The leaders spoke about Putin’s despicable blockade of Odesa, Ukraine’s biggest shipping port.

“The Prime Minister outlined to President Zelensky the intensive work taking place with international partners to find ways to resume the export of grain from Ukraine to avert a global food crisis.

“He said that the UK would work with G7 partners to push for urgent progress.

“The leaders agreed next steps and the imperative for Russia to relax its blockade and allow safe shipping lanes.”

Earlier this week, the Mr Johnson said the West was supporting the Ukrainians to demine the Black Sea and reopen international shipping lanes.

In an interview with Bloomberg on Friday, the Prime Minister said the Royal Navy would not be able to play any part in minesweeping the Black Sea, as the Montreux Convention restricts the movement of warships through the Turkish Straits.

But he said efforts were being made to aid Kyiv in finding solutions to the problem.

He said: “I think there is an absolutely appalling situation, which is when so much of the world is facing food price inflation, if not actual shortages of food, caused by what’s going on in Ukraine, caused by Putin’s war of choice.

“He decided to invade Ukraine, he had no reason to do it and it is he who is making it difficult to get 25 million tons of grain from those Black Sea ports, particularly from Odesa.

“Twenty-five million tons is equivalent to the entire grain consumption of the poorest countries in the world, and we’ve got to get it out.”

Russia has suggested the blockade could be relaxed in return for international sanctions being eased but Mr Johnson said president Vladimir Putin was “completely not to be trusted”.