Security measures have been tightened across Britain as German police continue to hunt for the suspect behind the Berlin lorry attack which left 12 dead.
British police are reviewing security arrangements for the festive period in the wake of the attack on Monday night and forces will be stepping up security measures at major Christmas markets.
Members of the public were urged to remain vigilant and report any concerns, as the official threat level in the UK remains at severe - meaning an attack is seen as "highly likely".
A 23-year-old Pakistani asylum seeker was detained in the aftermath of the attack in the German capital but denied any involvement. German police have admitted the person behind it may still be armed and at large.
Federal public prosecutor Peter Frank said the "modus operandi" of the attack had echoes of July's atrocity in Nice, in which 86 people died, and could have been the work of Islamic extremist groups, with the target of the attack "highly symbolic".
On Tuesday night Islamic State claimed responsibility for the attack that killed 12 people and injured 50.
Eleven people died when the articulated lorry careered through huts and stalls at the Christmas market near Kaiser Wilhelm Memorial Church, along with a Polish man found shot dead inside the lorry's cab.
Six of the 12 victims have been identified as German.
German chancellor Angela Merkel and senior officials visited the scene of the attack on Tuesday, laying white roses among candles at a makeshift shrine to the dead and injured.
Prime Minister Theresa May paid tribute, saying events in Berlin had "shocked us all" as she offered condolences to those affected.
The carnage in the German capital came hours after Russia's ambassador to Turkey was gunned down at a photography exhibition in Ankara.
The attack has led to heightened security concerns in the UK, though a Number 10 spokesman said there were "no plans" to change the UK's security level.
Scotland Yard said it has "detailed plans for protecting public events over the Christmas and New Year period".
Britain's largest force said: "These already recognise that the threat level is at severe, meaning an attack is highly likely, and have considered a range of threats, including the use of large vehicles.
"As a matter of routine, as a precaution, we review our plans after attacks overseas, and we are doing so at present following the awful incidents in Berlin and Ankara last night."
Huge numbers of people will be in London over the holiday season as shoppers flock to the capital for the post-Christmas sales, while more than 100,000 revellers are expected to attend the New Year's Eve fireworks display.
Greater Manchester Police said they had strengthened their presence at Christmas markets, which have almost 350 stalls spread across 10 sites in the city.
Assistant Chief Constable Debbie Ford said: "I would like to stress at this point that there is absolutely no information or intelligence suggesting any attack is imminent in Greater Manchester."
West Midlands Police said they were also reviewing security measures and increasing patrols in Birmingham, to ensure the safety of visitors to the city's popular Christmas German market.
The Met also announced that it would it be bringing forward enhanced security measures for Changing the Guard at Buckingham Palace, and implementing road closures during the ceremony.
National Police Chiefs' Council lead for protective security, Deputy Assistant Commissioner Lucy D'Orsi, said it was "routine" to review and assess security measures following incidents like the attacks in Germany.
"I would like to reassure everyone that the police, along with the security and intelligence services, are tirelessly working together to deal with the terrorist threat to keep the public safe," she said.