(BBC) David Cameron has made a statement at Downing Street, saying the threat from the so-called Islamic State is “evolving”, and becoming more acute.
“We in the UK face the same threat,” he said.
“We will redouble our efforts to wipe out this poisonous extremist ideology.”
In the light of last night’s attacks, the UK will review its terror plans and attempt to learn from what happened in Paris, he said.
Mr Cameron called the attacks the “worst act of violence in France since World War Two”.
He said Britain stands with France “shocked but resolute, in sorrow but unbowed”.
“While full picture is still emerging, we must be prepared for a number of British casualties, and we will do whatever we can to help those in need.”
Queen ‘deeply shocked and saddened’
The Queen has sent a message to President Hollande, saying: “Prince Philip and I have been deeply shocked and saddened by the terrible loss of life in Paris. We send our most sincere condolences to you, the families of those who have died and the French people.”
Boris Johnson: “They will not succeed”
Boris Johnson, the Mayor of London, has spoken about the attacks in Paris, which he called “our sister city”.
“I have written this morning to Mayor Hidalgo to convey the sense of shock and grief of millions of Londoners at the tragic events in Paris. Our thoughts today are with the victims and their families and with the whole French people.
“We regard Paris as our sister city, a place for which we have deep reserves of love and admiration and respect. We are two capitals united in our values – democratic freedom, openness and tolerance.
“The people who launched the attacks last night have no such values. They wish to undermine the things we hold most precious. They want to set neighbour against neighbour. They want to spread fear.
“They will not succeed. As president Hollande has rightly said, they must and will be defeated. We stand ready in London to do everything in our power – to do whatever it takes – to assist in a struggle that embraces us all.”