Berlin truck crash
People leave flowers and candles at the area after a truck ploughed through a Christmas market in Berlin, Germany Michele Tantussi/Getty Images

German police arrested two men on suspicion of planning an attack on a shopping mall in Oberhausen near the Dutch border.

The brothers, aged 28 and 31 and originally from Kosovo, were arrested in Duisburg, Germany in the early hours of Friday. The European country is on high alert since an attacker killed 12 people at a Christmas market in Berlin on Monday.

In a statement, Essen police said, "Friday morning (23 December, around 00:45 hours) special units in Duisburg took two suspicious men into custody.

"The 28-year old and 31-year-old brothers born in Kosovo are suspected of having prepared a possible attack on the CentrO in Oberhausen."

Police in the nearby city of Essen said that investigators were trying to glean information on the stage of preparation the brothers were on and also if others were involved. They added that they were tipped off by intelligence services. Police were deployed at the shopping mall and a Christmas market close by late Thursday.

The targeted mall, CentrO, is reportedly one of the biggest malls in Germany with almost 250 shops. It is situated in the former industrial heartland of the Ruhr valley.

Meanwhile, a manhunt is underway for Tunisian born Anis Amri, who is suspected of driving a truck into the Breitscheidplatz Christmas market in Berlin. There is no indication if the arrest of the two brothers is related to the Berlin attack.

Police have confirmed that Amri's fingerprints were found inside the lorry that was used to kill 12 people and injure 49 others.

Anis Amri: Video uncovered of Berlin Christmas truck attack suspect Reuters