U.N. Commission of Inquiry on Syria issued a statement on Wednesday urging states supporting Syria’s peace process to stop the warring parties from attacking unlawful targets such as hospitals and other civilian sites.

Air strikes, bombardment and rocket fire had been consistently used in recent attacks on civilian areas, the U.N. war crimes investigators said in a statement.

“Failure to respect the laws of war must have consequences for the perpetrators,” the commision’s chairman, Paulo Pinheiro, said.

“Until the culture of impunity is uprooted, civilians will continue to be targeted, victimized and brutally killed.”

According to international law, all parties to the conflict must distinguish between lawful and unlawful targets, but that distinction had been ignored and some recent attacks had been war crimes, the statement said.

It cited an attack on the al-Quds hospital in Aleppo governorate on April 27 and other attacks on nearby medical facilities, and air strikes on markets, bakeries and a water station, as well as the May 5 attack on a refugee camp in Idlib.

Those attacks all happened after a two-month ceasefire, engineered by Russia and the United states, unraveled, and Syrian government forces said they would launch an assault to recapture rebel-held areas of Aleppo.

The statement did not explicitly attribute blame for attacks on civilians, but only Syria’s government and its ally Russia are using aircraft in the conflict.

U.N. High Commissioner for Human Rights, Zeid Ra’ad al-Hussein, said last week that initial reports suggested Syrian government aircraft were responsible for the attack on the refugee camp in Idlib governorate, which killed about 30 people. Syria’s military denied that they had targeted the camp.