Concrete bollards used to prevent New Year's Eve lorry attack in London

Police have erected concrete barriers in Central London this evening to prevent a potential New Year's Eve lorry attack, as celebrations commence in the capital.

Concrete bollards have been placed at junctions to block traffic from crowds, as 100,000 people are expected to flock to the banks of the River Thames to watch the annual fireworks display.

Armed police will also be deployed on Tube trains for the first time on New Year's Eve as security is heightened following a police review.

The extra security measures were taken after Anis Amri ploughed a lorry into a gathering at a Berlin Christmas market earlier this month, killing 12 people.

In July, Mohamed Lahouaiej Bouhlel killed 86 people when he drove a 19-tonne lorry into crowds on Nice's seafront promenade.

The Metropolitan Police confirmed security plans for the capital's New Year's Eve celebrations had been "adjusted" in the last few days including both overt and covert" measures, to avoid a copycat attack, but confirmed that police are not responding to any specific intelligence of a threat.

Superintendent Phil Langworthy told Sky News: "Clearly we have been looking at what has happened around the world in terms of Berlin, Nice etc ... and have adjusted our plans and continue to adjust our plans."

3,000 officers are already mobilized in the city and will be supported by additional patrols, with British Transport Police working extended hours on New Year's Eve for the second year in a row.

Regional forces are also on alert as celebrations take place across the country. West Midlands Police said: "While the security status remains at severe we have further resources in place should they be needed."

In Scotland, some 80,000 people are expected to gather in Edinburgh's city centre to celebrate Hogmanay.

Police Scotland said it has also "reviewed" safety plans following the truck attack on a Christmas market in Berlin.

Chief Superintendent Kenny MacDonald said: "We are absolutely confident that the plans that we have in place are proportionate and appropriate, and we will make sure that we deliver a safe event."