Austria has not seen scenes like those in the German city of Cologne on New Year's Eve, when hundreds of women told police they had been groped, attacked and robbed by mobs of men.
But immigrants have been accused of isolated sexual and other attacks committed in Austria, which has helped harden public opinion against an open-door policy toward migrants fleeing war and poverty in the Middle East and elsewhere, as the Cologne episode did in Germany.
The far-right Freedom Party, which is running first in opinion polls, has seized on cases in which immigrants have been accused of crimes to press for stricter immigration policies. Immigration is likely to be a central theme in the re-run of a presidential election on Oct. 2.
The nine Iraqi men arrested in Vienna and two other provinces over the weekend are aged between 21 and 47 years and deny any wrongdoing, a police spokesman said. All have either applied for, or been granted, asylum.
They are accused of assaulting the German woman, who was visiting a friend in Vienna, in an apartment where two of the men were staying.
"The presumed perpetrators are likely to have taken advantage of the female victim's high level of inebriation," the Vienna police said in a statement.
The woman, from the northern German state of Lower Saxony, was celebrating at a square in central Vienna and does not remember what happened between about 2 a.m. and when she woke in the apartment around 6 a.m., the police spokesman said.
(Reporting by Francois Murphy; Editing by Richard Balmfort