German police say two Kosovo-born brothers were arrested in the early hours on December 23 on suspicion that they were plotting an attack on a shopping mall in western Germany.
The suspects, aged 28 and 31, were arrested in the city of Duisburg after receiving a tip-off from the intelligence services, police said in a statement.
Police suspect that the men may have been planning an attack on the Centro mall in nearby Oberhausen in the West German state of North Rhine-Westphalia.
The Centro mall is one of the largest in Germany with around 250 shops that are usually packed in the run-up to Christmas.
Police say they have increased their presence at Centro and a nearby Christmas market.
It was not clear if there was any link with the December 19 attack on a Berlin Christmas market that killed 12 people. Police are searching for a Tunisian suspect in connection with that attack, which was claimed by the Islamic State extremist group.