The papers: Hunt for David Haines's killers

In the aftermath of the murder of British aid worker David Haines by jihadists in the Middle East, the issue of how to deal with the threat posed by Islamic extremists is foremost in the UK's press on Monday.

The Times leads on David Cameron's vow to "hunt down" the killers of Mr Haines.

The paper notes the prime minister is to seek UN sanction for possible air strikes against IS militants next week, but Russia may veto the move.

The Times adds that US secretary of state John Kerry says he has won the backing of 10 Arab countries for attacks on the extremists - who control much of northern Iraq and eastern Syria.

Egypt, Iraq, Jordan, Lebanon and six Gulf states including Saudi Arabia and Qatar, have signed up to Mr Kerry's plan, with some offering troops.

A "senior source" tells the Guardian that Saudi Arabia felt so threatened by IS that it "was prepared to act in a frontline role".

"There is a very real possibility that we could have the Saudi air force bombing targets inside Syria. That is a remarkable development, and something the US would be very pleased to see."

But the paper notes all is far from agreed.

Turkey says it will not allow one of its airbases to be used for strikes into Syria, and Egypt and Saudi Arabia want to extend the scope of the campaign to tackle Islamist groups in the Sinai Peninsula and Libya.

The Daily Mail notes that Mr Cameron is under pressure from his own MPs to take action sooner rather than later.

Tory MP Col Bob Stewart tells the paper: "These people [IS] are not going to negotiate with us. The only way to deal with them is to destroy them."

The Daily Express's leader column agrees.

"Our national security and our way of life are under threat in a manner not seen since the defeat of Nazi Germany," it says.

"The sooner we carry out air strikes to end this depravity, the better for us all."

Writing in the Daily Telegraph, Boris Johnson says: "We would be mad not to use our defence capability, where we can, to make the world a better place."

However he cautions: "No one has yet put forward a convincing plan for removing Isil [IS] that does not mean some kind of ground commitment - and that we are determined to avoid, for very good reasons."

The Sun publishes a large picture of "Jihadi John" the British-sounding man thought to have been responsible for beheading Mr Haines, and two US captives.

It challenges the masked extremist to reveal his face, in an editorial branding him a "coward" without the bravery of the men whose lives he allegedly took.

Most papers focus on the plight of Alan Henning, the British taxi driver, who was seized in Syria by extremists when volunteering to take aid to Syria on behalf of a group of his fellow Manchester cabbies.

The 47-year-old was paraded for the camera in the video the fanatics made showing the death of Mr Haines.

One of his fellow volunteer aid workers tells the Sun: "Alan is an amazing guy - one of the best.

"I could tell a lot of stories about the good Alan has done and about how, as a non-Muslim, he has helped Muslims who've suffered in the conflict."

The Guardian says the married father-of-two has been described as a "big man with a big heart".

He was seized at Christmas shortly after crossing the Turkish border with other volunteers in a convoy of ambulances carrying food and medical supplies.

In the Daily Mirror, BBC journalist Catrin Nye tells of meeting Alan as his convoy prepared to leave for the war zone.

"He described how visited a refugee camp, and had a life-changing experience... holding the children had really affected him. It had really touched him and he had a desire to go again and help," she tells the paper.

Elsewhere in the paper, Sughara Ahmed, the president of the Islamic Society of Britain writes, "IS is an illegal group, an un-Islamic group, and we should treat it like any other criminal organisation.

"I also believe we should stop calling these people Islamic State. We should not give them any more credence. We should adapt the title to create a more fitting name.

"They are not associated with Islam. Islam doesn't sanction the cruelty they are perpetrating."

With the Scottish referendum rushing up to meet us, the papers main focus in the debate on Monday is to examine the utterances of the Queen.

The Daily Telegraph says the monarch, "spoke out... about the potential break-up of the United Kingdom by warning Scots to think 'very carefully about the future' before casting their votes" in the referendum.

The paper adds that while Buckingham Palace insisted her remarks were "politically" neutral, "they were being viewed last night as the clearest sign yet that she hopes for a No vote on Thursday."

The Queen made the comments in exchanges with well-wishers outside the church near Balmoral Castle.

The Queen had listened to a service which included a prayer asking God "to save us from false choices", the paper adds.

The Telegraph's chief reporter Gordon Rayner says: "The Queen simply does not make such comments by accident.

"When the Head of State of the United Kingdom urges people to think "carefully" about their vote, what other conclusion are we to draw than that she is concerned the Scots will take a rash step into the unknown by voting Yes?"

Peter McKay in the Daily Mail asks: "Is Salmond planning to ditch the Queen?"

McKay says the SNP leader "brushed aside" a question on the BBC's Andrew Marr programme about republican calls within his party.

The columnist notes that Mr Salmond - who insists the Queen would serve as head of state of an independent Scotland - has not always been a noted monarchist.

"In 1982, he and others were expelled from the SNP after being accused of belonging to a splinter group plotting left-wing and republican policies," McKay says.

"Later, he came to realise that overt republicanism was an obstacle in converting Tory, Labour and Liberal Scottish voters to nationalism."

"The monarchy is the elephant in the room during this referendum debate," he concludes.

To read what the Scottish papers have to say about the independence debate, see BBC Scotland's paper review.

Parents of teenage children may dispute this, but Britain is in the grip of a new wave of sober, sensible 13-18 year olds, it appears.

The Daily Telegraph headlines "teenagers turn away from sex, drink and drugs".

The paper notes that new statistics from the Health and Social Care Information Centre show the number of teenage pregnancies and abortions has dropped sharply, under-aged drinking is down and drug consumption appears to have halved since 2003.

The Telegraph says an increase in young people from "conservative migrant backgrounds" is partly credited with the figures.

The Daily Express quotes Prof Fiona Measham, of Durham University, who says "many youngsters are now more likely to spend time knitting than sitting in a pub".

"There isn't that frenzied drunkenness. There's a new sense of sobriety among young people."

The Daily Mail reckons Facebook and Twitter have eclipsed the old teenage vices.

The paper explains that social media means "youngsters increasingly spend time at home in their rooms rather than out on the streets."

Smoking, in particular, is at a 30-year low among the young, with just 3% of school pupils admitting touching a cigarette in the week the survey was carried out.

The Mail notes carefully designed "dummy questions" were included in the study to weed out those likely to "boast or exaggerate" about their habits.

The paper illustrates its article with a cartoon of a teenage girl standing sternly over a slumped man who is surrounded by beer cans.

"Bed, dad! You've got work tomorrow!" the young woman says.

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