CAIRO, Nov 9 (Reuters) - Arab foreign ministers will hold an emergency meeting next week to discuss Wednesday's killing of 18 Palestinian civilians by Israeli artillery fire in Gaza, the Arab League's Secretary-General Amr Moussa said on Thursday. "The message from Israel is clear, that it will be stopped by no one. And as such Arab countries must take up their responsibilities," Moussa said after a meeting of Arab representatives to the Cairo-based organisation. Moussa said the foreign ministers would try to forge a common Arab stance to confront Israel's policies. He said the League hoped that the United States, Israel's chief ally, would deal with the issue objectively. "We hope the United States will re-examine many of its policies which led to anger and the reactions it saw and continues to see in the Middle East and elsewhere." Most Arabs say Washington's support of Israel makes reaching a solution to the prolonged conflict difficult. Moussa also said the League would back calls by Palestinian officials for an international fact-finding mission into the killings, which he described as a "massacre."