BERLIN (AFP) - German authorities have arrested two brothers on suspicion of planning an attack on a shopping centre in the western city of Oberhausen, police said on Friday (Dec 23).

The two men aged 28 and 31 are originally from Kosovo, police said.

Germany is on edge after a truck was driven into a Christmas market in Berlin, killing 12 people and injuring almost 50 people.

Investigators were trying to establish what stage of preparation the plot was at and whether others were involved, police in the nearby city of Essen said in a statement.

Tipped off by the intelligence services, police were sent to the shopping mall and a nearby Christmas market late on Thursday, they said.

The mall that was targeted, CentrO, is one of the largest in Germany with around 250 shops that are usually packed in the run-up to Christmas. It is located in an old steelworks in Oberhausen in the former industrial heartland of the Ruhr Valley.

Police are still hunting for the perpetrator of Monday's attack on one of Berlin's most popular Christmas markets, believed to be a 24-year-old Tunisian.

The Islamic State in Iraq and Syria (ISIS) has claimed responsibility for the assault - its deadliest yet carried out on German soil.