US aid chief Samantha Power on Tuesday pledged $250 million in new funding to help Ukrainian farmers reeling from blocked Black Sea grain shipments since Russia's invasion last year, reported Reuters.

Moscow on Monday pulled out of a UN-brokered deal allowing the safe passage of Ukrainian grain through the Black Sea in a move UN Secretary-General Antonio Guterres called "a blow to people in need everywhere."

Speaking in the port of Odesa, Power said the investment, via a USAID initiative focused on Ukraine's agriculture sector, would aim to boost agricultural infrastructure and expand other export routes.

She also called on other governments and the private sector to match the US investment with another $250 million to help farmers "under attack" from Russia's policies and boost Ukraine's economy in the long term.

"We have a collective interest in ensuring that Ukrainian farmers stay in business," Power said during a briefing with Deputy Prime Minister Oleksandr Kubrakov during a visit to the Ukrainian port city of Odesa on Tuesday.

A day earlier, Power visited the State Emergency Services headquarters in the capital Kyiv, where she announced more than $500 million in humanitarian assistance.

She also handed over an additional $2.3 million worth of equipment to help the emergency services agency repair the damage inflicted by Russian forces on Ukraine's critical infrastructure.

Tens of thousands of Ukrainian civilians have been killed and millions have fled their homes since Russia's full scale invasion on Feb. 24, 2022, leading to Europe's biggest land war since World War Two.