BERLIN — A repeat of Austria’s presidential election should be postponed because of faulty postal ballots, the country’s interior minister announced on Monday in Vienna.

The minister, Wolfgang Sobotka, said that pushing back a rerun of the May presidential runoff, originally scheduled for Oct. 2, to late November or early December would require the approval of Parliament.

Mr. Sobotka said investigations had shown that several hundred ballots had been sent out and used, even though tests showed that adhesive flaps could be opened after being sealed.