Roundup: British PM vows to redouble efforts to wipe out "poisonous extremist ideology" after Paris attacks

Prime Minister David Cameron on Saturday said that the attacks in Paris were "the worst act of violence in France" since WWII, and the "worst terrorist attack in Europe for a decade."

Describing the attacks as "horrifying and sickening," Cameron said in a statement: "We will redouble our efforts to wipe out this poisonous extremist ideology."

Speaking at Downing Street, Cameron condemned the "brutal and callous murderers" in Paris attacks which killed at least 127 people.

In light of Friday night's attacks, he said, Britain would review its plans and "make sure we learn any appropriate lessons."

"It is clear that the threat from ISIL is evolving. Last night's attack suggests a new degree of planning and co-ordination and a greater ambition for mass casualty attacks," he added.

Showing solidarity with the French, he said: "Shocked, but resolute. In sorrow, but unbowed. My message to the French people is simple: Nous sommes solidaires avec vous. Nous sommes tous ensemble. We stand with you. United."

He warned Britons that the country "must be prepared for a number of British casualties," adding "we are doing all we can to help those caught up in the attack".

He spoke of the innocent victims killed and injured by brutal, callous murderers "who want to destroy everything our two countries stand for. Peace. Tolerance. Liberty. But we will not let them."

The prime minister noted that British police and intelligence agencies "work round the clock to do all they can to keep us safe."

Urging the public to "remain vigilant," he said: "we will do all we can to support our police and intelligence agencies with the resources and the capabilities they need."

"The terrorist aim is clear. It is to divide us and to destroy our way of life. So more than ever we must come together and stand united. And carry on with the way of life that we love, and that we know, and that will never be moved off," Cameron said.

Cameron said Britain's terrorist threat level was already at "severe", the second highest of all five possible threat levels, which means an attack is "highly likely".

Earlier on Saturday, Cameron chaired a cabinet emergency meeting to discuss British responses to the attacks.

He also spoke to French President Francois Hollande in a phone call. "I expressed our solidarity with France and said we will do whatever we can to help," Cameron said via his twitter account. Endit