Syrian rebels are seen in a bus as they are evacuated from the town of Douma, eastern Ghouta, Syria, April 1, 2018. Photo: Reuters / Bassam Khabieh.

Fighters have set fire to thousands of acres of wheat and other crops in northwest Syria in a campaign that has turned food supplies in a “weapon of war” and forced hundreds of thousands of civilians to flee, the United Nations said on Tuesday.

Satellite images released by campaigners last week showed fields, orchards and olive groves burning in the region where Syria’s Russia-backed army has been assaulting rebels in their last major stronghold.

Both sides in the fight had blamed each other for the destruction, the UN’s World Food Programme (WFP) said.

“The latest outbreak in violence in Idlib and north Hama has left dozens of casualties, burned several thousand acres of vital crops and farmland and forced at least 300,000 people to flee their homes,” WFP spokesman Herve Verhoosel said.

“Crops such as barley, wheat and vegetables have been destroyed. Destruction to farmland and the agricultural sector is unacceptable,” he told a news briefing in Geneva.

Farmers had not been able to get to their fields or tend to their remaining crops during the harvest season, as the warring sides vied for control and territory, Verhoosel said.

“The most important thing for us, it is not acceptable to take one more time the civilian population hostage, to basically use food, distribution of food as a weapon of war,” he added.

US President Donald Trump on Sunday urged Russia and Syrian government forces to stop bombing Idlib, following a Friday Kremlin statement that signaled Moscow would continue to back a month-long Syrian government offensive there.

Fires had also broken out in other areas away from the fighting, amid high temperatures, the WFP said. In all, less than 5 percent of Syria’s current crop had been affected, it added.