The weapons cache, which is thought to be part of unspecified foreign operations linked to Hamas, was discovered in a suitcase in a rented storage room in Vienna and contained five handguns and 10 magazines.
Austria's domestic intelligence service has uncovered a weapons cache in Vienna that is believed to be linked to the Palestinian militant group Hamas for use in "possible terrorist attacks in Europe," the government said on Thursday.
An unidentified 39-year-old British citizen with alleged "close ties to the weapons cache" was arrested in London on Monday, the interior ministry statement said.
"According to the current state of the investigation, Israeli or Jewish institutions in Europe were likely to be the targets of these attacks," it added.