Ukrainian and Russian leaders are accusing each other of blowing up a pipeline used to carry fertilizer.
The governor of the eastern Kharkiv region, Oleg Synegubov, wrote on social media on Tuesday that officials are assessing the damage from Russian shelling and the resulting leak of ammonia. The pipeline had been turned off, and Synegubov says the situation is "under control."
Russian leaders have a different version of events. They blame Ukrainian "saboteurs."
Foreign Ministry Spokesperson Maria Zakharova said on Wednesday that the Kyiv regime is the "only party not interested in resuming the pipeline's operations."
Russian negotiators insisted on restarting the line when they renewed an agreement to export grain through the Black Sea. Some diplomats fear this incident could put that deal at risk.
The two sides were already trading blame over the destruction of the Kakhovka dam, which has forced tens of thousands of people to evacuate. Leaders in Kyiv say the Russians blew it up to stop a Ukrainian offensive.
Ukrainian Prime Minister Denys Shmyhal said the "greater harm" posed by the "Russian act of terror" lies in the ecological devastation it inflicts on Russian-occupied areas of southern Ukraine. He added that the breach will leave those who live along the Dnipro river without drinking water and will threaten farmlands.
US officials say about 20,000 people need to be relocated. However, they admit they cannot "conclusively" say what happened.