Austria's interior ministry says its anti-terror units are investigating a threat from an unknown source to attack several police stations across the country.

Interior Ministry spokesman Karl-Heinz Grundboeck says the emailed threat was sent early Thursday from an anonymous address that has been used for previous similar threats.

He says the time the attacks were threatened to take place had passed without incident and that Austrian authorities "see no need at this time for panic-mongering."

However, he says in an email that "caution" was necessary at a time of heightened Europe security concerns.

The daily "Heute" newspaper says the threats were directed against 10 police stations.