The United Nations has said the detonation of hand-held communication devices in Lebanon could constitute a war crime as Beirut’s top diplomat accused Israel of orchestrating what he called a “terror” attack, AFP reports.

The blasts that killed at least 37 people and wounded nearly 3,000 on Tuesday and Wednesday targeted communication devices used by the Iran-backed Hezbollah group.

“International humanitarian law prohibits the use of booby-trap devices in the form of apparently harmless portable objects,” the UN’s High Commissioner for Human Rights, Volker Turk, told the Security Council during an emergency session on Lebanon requested by Algeria.

“It is a war crime to commit violence intended to spread terror among civilians,” he added, repeating his call for an “independent, rigorous and transparent” investigation.

“I am appalled by the breadth and impact of the attacks,” said Turk. “These attacks represent a new development in warfare, where communication tools become weapons,” he added. “This cannot be the new normal.”