UK steps up security as fears of fresh terror attacks increase

Scotland Yard is increasing both visible and covert policing at significant public events, such as the Wimbledon tennis championships which begin today, following Friday's terror attacks in Tunisia which claimed the lives of as many as 30 British citizens.

The attack, which the Islamic State (IS) has claimed responsibility for, represents the biggest loss of British life to terrorism since the 2005 London bombings, when 56 people - including the attackers - were killed. Although 18 Britons have been confirmed to have died in Tunisia, when gunman Seifeddine Rezgui opened fire at the beach resort of Sousse, the toll is expected to pass 30.

As many as 600 officers and support staff are involved in Scotland Yard's new security drive, making it the largest anti-terror operation since the London attacks of July 2005, according to the Metropolitan Police, who made the announcement over the weekend.

Today marks the first anniversary of the declaration of a caliphate across Syria and Iraq by the militant group, and Afzal Ashraf, a counter-terrorism expert, has warned that the timing of the multiple attacks last week is not coincidental. "The timing of the atrocious attacks in Tunisia, France and Kuwait suggest that these events could have stemmed from the same motivation: to mark the first anniversary of the forming of the caliphate which will be on Monday," he told one British newspaper.

"It is very likely IS will try to grab the headlines again in the next four or five days with another flurry of activity. This real risk will continue until the end of Ramadan, around 19 July," he continued.

Fears have been further raised by the National Crime Agency's warning that Czech-made Skorpion sub-machine guns have been trafficked into Britain. The Times newspaper reported the weapons are for criminal gangs, some of which have had dealing with extremists in the past, raising fears of a similar "lone wolf" jihadist attack on UK soil.

The UK prime minister, David Cameron, has pledged a "full spectrum" response to the massacre, and has written in the Daily Telegraph newspaper, saying that: "We must be more intolerant of intolerance – rejecting anyone whose views condone the Islamist extremist narrative and create the conditions for it to flourish."

"We are a target," said Cameron, speaking on BBC Radio 4's Today programme. "Frankly, we cannot hide from this thinking if you step back you become less of a target. They are attacking our way of life and what we stand for, and so we have to stand united with those that share our values."

Cameron also took the opportunity to denounce organisations which tacitly support extremist ideology. "There are some organisations, and some people, who buy not the terrorism but who buy a lot of the extremist narrative, and to those people we have got to say, that's not an acceptable view, and we are not going to engage with people who believe that there ought to be a caliphate, and women should be subjugated," he said.

He also urged the BBC not to refer to the self-described militant organisation as 'Islamic State', arguing that "the creation of this poisonous death cult is seducing too many young minds in Europe, America, the Middle East and elsewhere, and this is going to be the struggle of our generation."

The home secretary, Theresa May, has flown to Tunisia today for talks on how to address the extremist threat and to pay her condolences.

Scotland Yard announced it was tightening security and protection at Wimbledon and other "key sites, business and public places around the UK to help ensure they are safe for visitors and workers".