NEW YORK

UN Secretary-General Ban Ki-moon expressed concerned about reports of a deadly Russian airstrike on a school in northern Syria, a UN spokesman said Monday.

"If confirmed, today's attack would be a serious violation of international humanitarian law," Stephane Dujarric told reporters in response to a question by Anadolu Agency.

"The Secretary-General calls this and other similar attacks to be properly, effectively and independently investigated as to ensure more accountability," said Dujarric, noting that a recently adopted Security Council resolution "specifically demands that all parties immediately cease any attacks on civilians and civilian infrastructures such as hospitals and schools".

At least 17 people, including eight children, were killed Monday after a Russian jet bombed a school in the town of Ain Jara in Aleppo, local activists said.

Monday's massacre followed a series of air raids Saturday on the opposition-held Maarat al-Numan district in northwestern Idlib province. The attacks, blamed on Russian warplanes, left dozens of civilians dead, according to activists.

More than 570 civilians have been killed since Sept. 30 when Russia began airstrikes to prop up the regime of President Bashar al-Assad, according to a December report by the Syrian Network for Human Rights.

"The international community must act quickly against Russia’s flagrant crimes against the Syrian people including children, women and the elderly," said the Syrian National Coalition, Syria's main opposition group.

"Russia’s actions in Syria, while representing a continuation of Assad’s terror since the start of Syrian revolution, are designed to break the will of the Syrian people and undermine the political solution," the statement added.

The Syrian civil war, now in its fifth year, has left more than 250,000 victims dead and made the country the world's single-largest source of refugees and displaced persons, according to UN figures.