The exodus of Muslim refugees from Buddhist-majority Myanmar was sparked by a fierce security force response to a series of Rohingya militant attacks on police and army posts in the country's west on August 25.
The Islamist group behind the September 11, 2001, attacks on the Untied States issued a statement urging Muslims around the world to support their fellow Muslims in Myanmar with aid, weapons and "military support".
"The government of Myanmar shall be made to taste what our Muslim brothers have tasted."
Myanmar says its security forces are engaged in a legitimate campaign against "terrorists", whom it blames for attacks on the police and army, and on civilians.
The government has warned of bomb attacks in cities, and al Qaeda's call to arms is likely to compound those concerns.