(Adds U.N. comment)
PARIS, Oct 27 (Reuters) - French Foreign Minister Jean-Marc Ayrault said either Russia or the Syrian government were responsible for an air strike on Syria's Idlib province that led to the deaths of 26 civilians, most of them school children.
"Who is responsible? In any case it is not the opposition because you need planes to launch bombs. It's either the Syrians - the regime of (President Bashar) al-Assad - or the Russians," Ayrault told a news conference.
"It's yet another demonstration of the horror of this war, which is a war against the Syrian people, which we cannot accept."
Russia's foreign ministry said earlier on Thursday that Moscow was not responsible for the attack on Idlib.
U.N. Secretary-General Ban Ki-moon was appalled by the attack, which - if deliberate - may amount to a war crime, his spokesman Stephane Dujarric said. Ban called for an immediate and impartial investigation of all attacks against civilians.
"If such horrific acts persist despite global outrage, it is largely because their authors, whether in corridors of power or in insurgent redoubts, do not fear justice. They must be proved wrong," Dujarric told reporters.
United Nations envoy for global education, Gordon Brown, called on the U.N. Security Council on Thursday to "agree that the International Criminal Court prosecutor conduct an investigation into what I believe is a war crime."
"The Security Council should ask the International Criminal Court prosecutor for an investigation into what is happening in Syrian schools and in Syria as a whole," Brown told reporters.
Russia and China have protected Syria's government from Security Council action to try and stop the war, including vetoing a bid to refer the situation in Syria to the International Criminal Court in 2014.
Syria's war pits President Bashar al-Assad, backed by Russia, Iran and Shi'ite Muslim militias from Lebanon, Iraq and Afghanistan against mostly Sunni Muslim rebel groups including some backed by Turkey, Gulf monarchies and the United States.
(Reporting by Marine Pennetier in Paris and Michelle Nichols at the United Nations; Writing by Ingrid Melander and Michelle Nichols; Editing by Michel Rose and Chris Reese)
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