“We are at present largely no longer enforcing Dublin procedures for Syrian citizens,” said the note, posted on the account of the Federal Office for Migration and Refugees.

The bureaucratic tweet was the first confirmation of an online rumor that had begun to spread a day earlier: With more Syrian refugees arriving via Hungary and other European Union member states, Germany was using its prerogative to stop enforcing the bloc’s asylum rules that require all migrants to be processed in the first EU country they enter…

Within hours, the news contained in the obscure German-language message spread, amplified by news media and word-of-mouth.

Tributes to German Chancellor Angela Merkel poured in from Arabic social media: Photoshopped portraits of her emblazoned with such words as “the loving mother” and “Mama Merkel” began appearing on social networks frequented by Syrians. One lyrical Facebook user called her “pure-hearted” and “a lion.” Arabic references to “Merkel” on Twitter spiked from fewer than 500 a day on Aug. 22 to 2,000 by Sept. 3, according to Topsy, a social-media analytics firm.