Sir Edward Leigh, a Conservative MP, says his constituent Carly Lovett, 24, was killed in Tunisia last week. "She didn't deserve this, nobody deserves this," he tells MPs. The Gainsborough MP goes on to say that what worries people is that the threat is everywhere. Replying from the despatch box, Mr Cameron said it was a "heartbreaking story" and pays tribute to Ms Lovett.

Sadiq Khan, a former shadow justice secretary and Labour London mayor hopeful, says there can be "no justification" for the Tunisian terror attack. He asks what the government will do to work with communities to promote and defend British values.

Mr Cameron cites steps to combat radicalisation, and says more can be done to discuss with British Muslims how to confront the "poisonous ideology" of IS - including talking to Muslims "directly" rather that through "self-appointed leaders, that do not always represent the British mainstream".

"When we set the risk ratings for countries, we must take into account their capacity to mitigate against these threats," says David Cameron of the Foreign Office's travel advice on Tunisia.

Veteran Eurosceptic MP Bill Cash raises a (rather unhelpful, for the PM) question on the EU. He says European leaders are "clearly not listening" to the PM on EU reform, as they are "demanding more integration, not less". What will it take for the PM to recommend a no vote in the upcoming referendum, he wants to know? David Cameron tells him that he goes into these negotiations "an optimist" and says the indication from his meetings with his EU counterparts is that they are "open to reform".

Liberal Democrat Tom Brake extends his party's sympathies to the Tunisian beach attack victims and their families. He requests the PM to commission a report "on the role of Salafist reaching in fuelling support for violent actions against non-Muslims and Muslims", given "the link between the [Tunisian] terrorist and Salafist ideology".

Image source, AFP/Getty Images

David Cameron is fielding questions from backbench MPs. Tory Henry Bellingham asks him whether he agrees that social media companies' privacy policies are "completely unsustainable".

David Cameron says he raises an important point, adding that the government is urging social media companies to "work with us" and help in the fight against terrorism. Terrorists shouldn't have "a safe space to communicate", he says, adding that this will be a challenge that Parliament will have to consider.

Tunisia's transition to democracy is "the one ray of light coming out of the Arab Spring", but it is "as fragile as the economy and security", says the new Foreign Affairs Committee chairman, Crispin Blunt. He goes on to raise concerns about the "more than 20,00 Tunisians" that he says have tried to join IS.

David Cameron responds by saying it is crucial to help Tunisia on its political journey. He adds that it's too early to say whether the attacks last Friday we're co-ordinated.

Responding to Liam Fox's question, David Cameron agrees with the Tory backbencher that military action alone will not be enough, saying the terrorists' finances and narrative needs to be tackled.

Image source, PA

Liam Fox, Conservative former defence secretary, says not enough Arab states in the region are "pulling their weight". Individuals and states that "make and facilitate the spread of fundamentalist Islam" possible should be "named and shamed".

He also stresses the need to "rediscover" the "value of counter-propaganda", underlining the need to speak with "one voice and one message" about the values that have made us who we are and the freedoms that we have, what they are".

The SNP's Angus Robertson offers his party's sympathies to the families of those killed in Tunisia. He says it was an "horrific" attack. Mr Robertson goes on to say the PM was right to focus on the longer term challenge of extremism and radicalisation, and endorses the PM's call against calling IS, Islamic State, saying the politicians and media should call the militant group "Daesh".

On that point, Mr Cameron says the term Islamic State is seen as "particularly offensive" to many Muslims, as IS is "a barbaric regime of terrorism and oppression". He raised the case in his interview with the BBC Radio 4's Today programme this morning, saying ISIL would be better than IS, but he tells MPs: "I don't think that we will move them all the way to Daesh."

Adrian Bailey, Labour MP, says three generations of one family were killed in the Tunisian beach attack "atrocity", saying the impact on the family and local community has been "devastating". He backs his shadow cabinet's call for a dedicated taskforce to give these families support - and urges the PM to do the same.

Mr Cameron agrees it is a "heartbreaking" case, and says the first thing to do is ensure that every family has a "family liaison officer", telling MPs this is being put in place. The next step, he goes on, is thinking about how to mark what has happened, which should be done "in consultation" with the families affected. He adds that it's right to have a national commemoration.