The prime minister has said people should go about their business as usual and not be “cowed by terrorists” after the Christmas market attack in Germany.

Theresa May told the London Evening Standard it was important to “send a clear message that people should “carry on with our lives as usual”. She added that the police and security services were “unsung heroes”.

Twelve people were killed on Monday when a truck was driven into a crowd at the Breitscheidplatz market in Berlin. So-called Islamic State has said one of its militants carried out the attack but has offered no evidence.

The market has now reopened and police are searching for a Tunisian suspect, named as Anis Amri.

Mrs May told the Standard: “Of course our thoughts are with those who have been affected by the terrible attack that took place in Berlin, but Londoners should go about their business as usual. They should enjoy this Christmas period.” The prime minister added: “It is important, I think, that we send a very clear message that we will not be cowed by the terrorists – that we will carry on with our lives as usual.” She said: “The security services and the police are working day in and day out to keep us safe…. “They are often unsung heroes but they are actually doing a very good job. However, they have to be vigilant all the time and we should be very grateful for the work they do.”