Turkey announced that an agreement had been reached with Russia to allow Ukraine to continue exporting wheat through the Black Sea.

Ukraine, Russia, Turkey and UN Secretary-General Antonio Guterres are due to sign it on Friday in Istanbul.

A worldwide shortage of Ukrainian grain since the February 24 Russian invasion has left millions at risk of starvation.

But a Ukrainian lawmaker close to the talks expressed caution about the deal.

"We don't have an agreement yet.

We don't trust the Russians at all.

So let's wait until Friday for the final decision and that there will be no Russian rejection and last-minute changes," Oleksy Honcharenko, a representative in Odessa, told BBC 4's World Tonight show.

Due to the occupation, food prices have increased, so the agreement to unblock Ukrainian ports is crucial.

Ukraine's foreign ministry has confirmed that another round of UN-led talks on unblocking wheat exports will take place in Turkey on Friday - and that the document "may be signed".

The US State Department welcomed the UN-brokered deal but said it was focusing on holding Russia accountable for its implementation.

"We should never have been in this position in the first place.

This was a deliberate decision by the Russian Federation to use food as a weapon," State Department spokesman Ned Price said.

/Telegraph/