Three Red Cross workers have been killed after aid vehicles were “attacked” by Russia in eastern Ukraine, officials in the country have said.

The staff members, who were all Ukrainian, were unloading wood and coal briquettes to distribute to vulnerable households to help them prepare for the winter when the vehicles they were using were hit, the Red Cross said.

Prosecutors said two other Red Cross workers were hospitalised, with one in a serious condition, after the shelling in the Donetsk region.

Ukrainian President Volodymyr Zelenskyy called the deaths a “war crime” and said the Red Cross vehicles had been “attacked” by Russia.

The International Committee of the Red Cross (ICRC), a humanitarian organisation, said no civilians were affected by the shelling.

The organisation said its teams are regularly present in the Donetsk region and their vehicles are clearly marked with the Red Cross logo.

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ICRC President Mirjana Spoljaric said: “I condemn attacks on Red Cross personnel in the strongest terms.

“It’s unconscionable that shelling would hit an aid distribution site. Our hearts are broken today as we mourn the loss of our colleagues and care for the injured.

“This tragedy unleashes a wave of grief all too familiar to those who have lost loved ones in armed conflict.”

It comes as relief agencies and Western governments are ramping up civilian aid to Ukraine to protect its hospitals and power systems ahead of the winter as Russia continues daily airstrikes across the country to try and cripple its electricity infrastructure.

The World Health Organization (WHO) warned Thursday that the severe damage to energy and health facilities is leaving millions vulnerable as temperatures drop.

Since the start of Russia’s full-scale invasion in February 2022, the UN agency has recorded nearly 2,000 attacks on Ukraine’s healthcare infrastructure, which it said is having a severe impact on the largely public health system.

The Donetsk region, which Russian troops partially occupy, regularly comes under Russian shelling and airstrikes.

Moscow denies targeting civilians or civilian infrastructure in its invasion of Ukraine, although thousands of people have been killed in its attacks.