U.S. Special Representative for Ukraine Negotiations Kurt Volker has commented on a recent attack on personnel of Voda Donbasa's Donetsk Water Filtration Plant by Russian-led forces in eastern Ukraine, saying that targeting civilians is unacceptable.

"Very worrisome. Targeting civilians is unacceptable: #NotATarget," he tweeted on Tuesday evening.

Read alsoDonetsk water filtration plant's staff bus comes under fire, five wounded

As UNIAN reported earlier, five employees of the Donetsk water filtration plant were wounded when they were fired upon by small arms on Tuesday afternoon. They were going to work by bus. One of them is in a critical condition.

"In light of today's tragic incident, I wanted to share this info on how the Russia-led forces have encroached on the DFS [Donbas Filtration Station] over the last two years," he wrote, retweeting his tweet for December 19, 2017. He then shared satellite imagery showing the deployment of Russian troops close to the station.

"Russia-led forces are as close as 500 m from Donetsk Water Filtration plant. Need ceasefire and withdrawal of heavy weapons ASAP per Minsk agreements," his December 19 tweet said.

The station supplies water to towns and villages in government-controlled and Russian-occupied areas in Donbas: Avdiyivka, Krasnohorivka, and Verknetoretske, as well as the temporarily-occupied Donetsk, Yasynuvata, and the villages of Vasylievka and Spartak.

A spokesman for Voda Donbasa said the station might be completely shut down on April 18.