British police and spies are assisting French and Belgian counterparts in the manhunt for associates of the Paris terrorists.
Home Secretary Theresa May said the increased security measures put in place at UK ports and cities would remain in place as she vowed that Britain would stand "shoulder to shoulder" with France.
Speaking after chairing a meeting of the Government's Cobra emergency committee, Mrs May said the UK authorities were working to help find anyone involved in the "barbaric attacks" in the French capital.
She said: "The UK police and security services are working very closely with their counterparts in France and Belgium to identify all those involved and to pursue anyone who may have been involved in the preparation of these barbaric attacks.
"We will be maintaining increased levels of security at our borders and people will see an increased presence of police and Border Force at all ports."