Home Secretary Theresa May will chair a Cobra meeting later to discuss the UK government’s response to the attacks in Paris.
Britain’s terror threat level is “severe”, but Prime Minister David Cameron said it would reviewed.
Police said there would be strengthened policing at UK ports, and more officers at public events in the coming days.
It comes as Briton Nick Alexander, from Colchester, was named as among the 129 people killed in Friday’s attacks.
The 36-year-old died in the attack at the Bataclan concert hall, where he is thought to have been selling merchandise, reports the BBC.
Friends of Alexander also paid tribute to him on social media. Joe Trohman, lead guitarist of the rock band Fall Out Boy described him as a “great guy”.
The Bishop of Chelmsford, the Right Reverend Stephen Cottrell, said he was praying for Alexander’s family and had sent a message of support to their local church.
A government source said there were fears a “handful” of other British people had been killed. An unspecified number are being treated in hospitals.
