Police in the German city of Essen have ordered that a shopping centre remain closed on Saturday (11 March) due to "concrete indications" of a possible terror attack.

The country remains in a state of high alert after a 26-year-old Tunisian man ploughed a truck through a Christmas market in Berlin on 19 December 2016, killing 12 people.

Months on, terror police in Germany said they have indications of another attack, without providing further details.

"The current state of our investigations points to the threat being exclusively at the shopping center," said the police in a statement seen by Reuters.

The Limbecker Platz Essen shopping centre in central Essen also released a statement via Facebook confirming the closure.

"The Limbecker Platz remains closed this Saturday for safety reasons," a spokesman said.

"The Police are warning of a possible attack and the closure is due to a possible threat to visitors. We ask for your understanding."

Dozens of special forces were deployed to the shopping centre, said to be among Germany's biggest according to local media, following the decision to keep it closed on Saturday.

Der Spiegel reported that several staff arrived to open up their respective stores, but were quickly evacuated from the building.

It follows warnings from German intelligence officials in recent days that the terror threat is still high.

Hans-Georg Maassen, president of the Federal Office for the Protection of the Constitution, said his office received 20 tips regarding credible threats since the New Year, which it was investigating.

The British Foreign Office has not warned against travel to Germany, but said people needed to remain vigilant.

"There is a high threat from terrorism," a spokesman said. "Attacks could be indiscriminate, including in public places visited by foreigners.

"The German government has announced that increased security has been put in place as a precaution at public buildings, major events, transport hubs and large public gatherings.

"There is considered to be a heightened threat of terrorist attack globally against UK interests and British nationals, from groups or individuals motivated by the conflict in Iraq and Syria. You should be vigilant at this time."

Limbecker Platz terror
Police secure the area at Limbecker Platz shopping mall in Essen, Germany on 11 March 2017 Reuters