Britain is ready to cope with an attack the scale of the suspected suicide blast on the Moscow subway, according to the emergency services.
London "prepared" for an attack similar to the one in Moscow
The London Ambulance Service said it was confident it could deal with a similar outrage.
"We have coped with disasters such as the Paddington and Southall crashes and King's Cross fire," a spokesman said.
Attacks on the scale of the Moscow blast would be "extremely difficult" but "manageable", he said.
Measures for dealing with the aftermath of bigger attacks, such as a prospective dirty bomb, were being revised in cooperation with the government, the spokesman added.
"Resources needed would depend on the types of injuries sustained and we would call on back-up support from voluntary agencies such as the Red Cross and St John Ambulance, as well as nearby ambulance services," he said.
At least 39 people died and more than 100 were injured in the rush-hour attack in Moscow, which President Vladimir Putin has blamed on Chechen rebels.
Mick Shaw, of the London Fire Brigade Union, said the Moscow attack showed the need to have proper emergency resources available "24 hours a day, seven days a week", but was confident the brigade could handle a similar attack.
He said: "We currently have five special rescue units equipped with extended duration breathing apparatus. This is being doubled later in the year.
"We have also had a general increase in staff of 200 in London over the past year, thanks mainly to funding from the mayor."
Mike Strzelecki, director of safety for London Underground, said LU had taken the threat of terrorists targeting the Tube "very seriously" for many years.
"We are constantly vigilant and work with our colleagues in the London Resilience team and the police to reduce the risk to our customers and staff."
London Resilience, a consortium of emergency services and transport operators, says much has been done to address the threat from terrorism to the capital.
But it warns more people and specialist equipment may be needed to cope with such an emergency.
Last September, hundreds of emergency personnel were involved in a rescue operation during a simulated chemical attack at Bank Tube station in the City of London.
A London Resilience report on the exercise claimed masks had interfered with communication between emergency workers, and called for improvements in protective suits.
Mayor of London Ken Livingstone has warned that the threat to London from terrorism remains "real and serious".
A spokeswoman at his office said: "A great deal of work has been carried out to make sure London is as well prepared as we can make it for such a catastrophic incident.
"London emergency services have a great deal of experience in dealing with this kind of disaster, honed by 30 years of dealing with terrorist attacks."
Mr Livingstone has written to his Russian counterpart expressing sympathy over the attack and offering the assistance of the London Resilience partnership, of which he is vice-chairman, in dealing with its aftermath.