An Air Berlin flight took off from the Namibian capital after the airline rechecked its luggage following a suspicious suitcase found inside the airport.

German authorities say that a suitcase with a fuse was found inside the luggage hall of the airport in Windhoek, Namibia on Wednesday morning. It was found in a part of the luggage hall where the Air Berlin flight bags were being stored nearby.

The fuse was attached to a clock and to batteries, and Namibian authorities were trying to determine if it could have exploded.

But Air Berlin spokesperson Sabine Teller said no explosives were inside the suspect luggage.

All of the luggage on board the flight was rechecked and passengers were asked to identify their bags. Following the extra security checks, Teller said that no bags were unaccounted for.

The plane later took off from the Namibian airport and landed in Munich on Thursday morning.

The incident comes at a time when German officials have signalled that the country is facing a possible terror attack.

Thomas de Maizier, the country's interior minister, said Wednesday that German intelligence officials believe terrorists could be planning an attack for the end of this month.

De Maizier said German authorities received a tip on the threat from another country and have also found their own evidence of "sustained efforts" by Islamist extremist groups to plan attacks on Germany.

"Besides the previously known findings, we now have additional, relevant indications of possible danger that security authorities agree justify our current assessment that we are now facing a new situation," de Maizier said.

In response to the threat, German authorities have beefed up security at airports, train stations, ports and other public areas.

Kate Connolly, a reporter for London's Guardian newspaper, said the increased security presence has made Germans highly aware of the threat the government is reporting.

"People just seem to be … a little bit more nervous," Connolly told CTV's Canada AM from Berlin on Thursday morning.

"They have been warned to look out for any suspicious packages or any suspicious persons at (train) stations and airports in particular."

Connolly said there is a sense in Germany that a terror attack is inevitable, based on the attacks that have targeted Madrid and London in recent years and the fact that the country is involved in the war in Afghanistan.

With files from The Associated Press