The Saudi-led coalition fighting rebels in Yemen said on Sunday it will investigate an air raid that killed more than 140 people at a funeral, after Washington announced it was reviewing support for the alliance. The Iran-backed Houthi rebels blamed the coalition for Saturday’s attack, one of the deadliest since it launched a military campaign against the Shiite insurgents in March 2015. The attack could further sour U.S.-Saudi ties already strained over the coalition’s military intervention which is suspected of causing almost half of the more than 4,000 civilian deaths in Yemen’s conflict. It also risks embarrassing Washington, which has vehemently criticised Moscow over the heavy civilian death toll from Russian air raids in support of Syria’s regime in Aleppo city. After initially denying any responsibility, the coalition said it was ready to launch a probe into the “regrettable and painful” strike, which the UN said also wounded more than 525 people. “The coalition will immediately investigate this case along with… experts from the United States who participated in previous investigations,” it said. “The coalition is also willing to provide the investigation team with any data and information related to its military operations today, at the incident’s location and the surrounding areas.” UN chief Ban Ki-Moon demanded a “prompt and impartial” probe. “Those responsible for the attack must be brought to justice,” he said. The Houthis accused the coalition of a “massacre”, saying its planes hit a gathering of hundreds mourning the death of the father of rebel Interior Minister Jalal al-Rowaishan. Thousands of angry protesters took to the streets of Sana’a on Sunday, chanting slogans against Saudi Arabia and the United States. Yemen’s rebel-allied former President Ali Abdullah Saleh called on Sunday for mobilisation along the border with Saudi Arabia to avenge the deadly air strikes. ”I call upon all members of the armed forces, security and popular committees [militia]… to head to the front, to the borders, to take revenge,” he said in a televised address. “We should avenge our casualties… those killed in army bases as well as in markets, including heinous massacres, and the greatest of those is the massacre of the (funeral) hall,” which was struck on Saturday. Mr. Saleh, who stepped down in 2012 following nationwide protests and a Saudi-sponsored peace initiative, commands troops that have defected and sided with Iran-backed Shia rebels, who overran the Yemeni capital in 2014.