'No zero terror risk', EU security chief warns

But he said the EU member states will make further attacks difficult, therefore as unlikely as possible.

“We are making progress on these efforts, but we need to keep going,” he said. Calling on member states to make use of all the information sharing instruments available to them, he highlighted the Schengen information sharing system (SIS).

“I don’t think it was a complete accident that this attack took place on the first anniversary of the Brussels attacks,” he added.

King said the methodology of the London attacker fits into a pattern of behaviour witnessed in Nice and Berlin last year, with a vehicle repurposed as a weapon against the softest targets. “People like us going about their daily lives”, he said.

Even before the London attack, the terrorist threat was extremely high across Europe, the UK commissioner said.

"This is an attack on our democracy that is felt and shared understanding across the EU," King added.

"They target our way of life and values, we are not going to let them win,” he said, adding that it was right for France to go ahead with the European football championships last summer and Germany to keep the Christmas markets open in December.

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Other politicians in Europe tried to forge political gains from the London attacks.

Former UKIP leader and pro-Brexit campaigner Nigel Farage took the time to appear on US television, using the London attacks to support US president Donald Trump's anti-immigration and anti-Muslim policy.

"When Donald Trump tries to make America safer, when Donald Trump tries to make sure that these scenes we’ve had in Paris, Brussels, Berlin and now London aren’t repeated in America, we have people on Fifth Avenue and behind me in Westminster out on the streets protesting. It seems to me that our political leaders really ought to start saying sorry," Farage said on Fox News on Thursday.

Farage laid the blame on UK politicians for not putting in place tougher migration controls to avoid terrorist attacks.

France's far-right leader and presidential candidate Marine Le Pen said on Thursday that the attack underscored the need for tighter border controls.

Le Pen's campaign centers on anti-immigration, stricter border controls. The London terror attacks play into that, as three French schoolchildren were among those injured.

"The problem we have nowadays is this form of low-cost terrorism," she said, adding that "we must control our borders".

Europe's new enfant terrible, Poland's prime minister Beata Szydlo linked the London attacks to the EU's migration policy.

Poland has refused to accept the roughly 6,200 asylum-seekers from Greece and Italy it is obliged to take in under the EU's migrant relocation quota plan, designed to ease the burden on frontline member states.

Szydlo said the attack vindicated Warsaw's refusal.

"I hear in Europe very often: do not connect the migration policy with terrorism, but it is impossible not to connect them," Szydlo told private broadcaster TVN24.

Szydlo's ally, Hungary's prime minister Viktor Orban has already made that link in early 2015 after the killing of Charlie Hebdo journalists at the satirical paper's office in Paris.