Armed police will be deployed on London Underground trains for the first time on New Year’s Eve following a review of security.
The additional armed patrols have been brought in to bolster the 3,000 officers who will police the capital’s streets.
Although armed officers have been visible at Tube stations for some time, they are not routinely seen on Underground trains and platforms.
Concrete barriers have also been erected around the main routes into London to guard against the possibility of a vehicle attack.
The Metropolitan Police confirmed that security plans for the Mayor’s firework display – and surrounding New Year’s Eve celebrations – had been “adjusted” in the last few days.
It has happened because concerns about a possible mass-casualty terror plot targeting the event have intensified following events in Nice and Berlin.
A lorry drove along a packed seafront in Nice in July, killing 86 people, while 12 people died earlier this month when another lorry was driven into Christmas market stalls in Berlin.
Superintendent Phil Langworthy, from the Metropolitan Police, said: “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.
“We police around 3,500 large events every year, including New Year’s Eve, and we meticulously plan those events.
“We have meticulously planned New Year’s Eve, and we look at our tactics and we look around the world and adjust our tactics if need be.
“We have a very extensive planning period – we plan for many months.”
He added that there were “both overt and covert” measures in place for security.
He said there was “no specific intelligence” about an attack on the New Year celebrations, but added: “I would encourage people on the night, if they see anything suspicious or have any concerns, to come and speak to one of the police officers or stewards who will be on duty.”
Large crowds are expected to attend the event on the banks of the River Thames, as well as in Trafalgar Square and other areas.
The firework display is a sold-out event, and police are encouraging anyone without a ticket to stay at home and watch it on television.
Road closures will be put in place from 2pm on 31 December in central London, including on Waterloo Bridge and Blackfriars Bridge.