British police stepped up security in potentially vulnerable areas of London in response to Sunday's US-British attack on Afghanistan.
"The Metropolitan Police Service is closely monitoring events which are unfolding and we have been vigorously planning for a range of threats which may impact on London," said a police spokeswoman.
High-visibility policing will continue and additional security is also being introduced to potentially vulnerable areas where needed.
The spokeswoman would not divulge details of the extra security measures or what might constitute a target of any terrorist attack.
She said the stepped-up police presence aimed to reassure minorities, who have increasingly come under attack since the September 11th attacks.
"We recognise this is a difficult and uncertain time for everyone and encourage members of all communities to go about their daily business as normal," she said.
Police in London, considered a potential terrorist target for Britain's strong support of the United States, have already put an extra 1,000-plus officers on the capital's streets since last month's attacks on New York and Washington.
A Home Office (interior ministry) spokeswoman said there was no specific threat to Britain at the moment, adding there were tried and tested contingency plans in place.