A suspected bomb with running clock has been found on an Air Berlin flight from Namibia to Germany.

Namibian police intercepted the suspicious object with a detonator and a running clock in luggage on the flight from Windhoek to Munich.

Germany’s Federal Crime Office (BKA) said it was not clear yet if the object found during loading of the Airbus jet was an ignitable explosive.

The discovery was made after Germany raised airport and railway security measures on Wednesday.

“A subsequent X-ray (of the luggage) revealed batteries that were attached with wires to a detonator and a ticking clock,” the German authorities said in a statement. “Only the ongoing forensic investigation will show whether this was a live explosive.”

The flight left Wednesday after a six-hour delay after all of its cargo had been removed, Air Berlin said in a statement.

The discovery comes after Germany on Wednesday received intelligence pointing to a planned attack towards the end of this month.

German Interior Minister Thomas de Maiziere said the threat against the country from “Islamic groups” had become “more serious” following a tip-off from an “international partner”.

“There is reason for concern, but no reason for hysteria,” he said.

“We have concrete indications of a series of attacks planned for the end of November.”

In response, German police has increased the level of alert at potential targets including transport hubs like airports and railway stations.

Karl Peter Bruch, the interior minister of the state of Rhineland-Palatinate, said there were “concrete indications” of terror attacks planned in major cities including Berlin, Hamburg and Munich.

On Thursday Konrad Freiberg, the head of Germany’s police union, warned that Germany was not prepared for a terrorist attack.

“We have missed a few steps along the way and there are security deficits that we have drawn attention to,” he told the Hamburger Abendblatt daily.