U.N. Special Advisor for Syria Jan Egeland attends a news conference at the United Nations in Geneva, Switzerland, August 17, 2017. REUTERS/Denis Balibouse

GENEVA (Reuters) - The United Nations condemned air raids on five hospitals and two humanitarian warehouses in Idlib, Syria, this week and called for setting up a system so warring sides would protect civilians and medical facilities near “terrorist” groups.

Jan Egeland, U.N. humanitarian adviser on Syria, said it was not clear who had carried out the attacks, but said it was part of an escalating trend to attack “humanitarian lifelines” including hospitals, ambulances and health workers.

“We urgently need a workable and respected system of notification for these protected localities that armed actors will respect,” he told reporters, although he conceded that some aid agencies were reluctant to share their GPS coordinates with the warring sides.