The savage murder of a man believed to be a soldier on a London street in a suspected terror attack was "beyond belief" but will only strengthen Britain's support for its armed forces, newspapers said Thursday.

Two suspected Islamists were arrested following the attack, which happened in broad daylight, but not before they had launched a filmed tirade against Britain's involvement in Afghanistan.

"We killed this British soldier. It's an eye for an eye," said the Sun's headline, quoting from the recorded message.

The Daily Telegraph ran with the headline "An eye for an eye, a tooth for a tooth. We won't stop fighting you until you leave us alone."

Also quoting the attacker, the Guardian carried the words "You people will never be safe," on top of a picture of the suspect waving a bloodied hand and wielding a meat cleaver.

The Daily Mail used the same picture on its front page above the headline "Blood on his hands, hatred in his eyes".

The Sun described the attack as "almost beyond belief" in its editorial.

The victim was believed to have been wearing a jumper supporting Help for Heroes, an armed forces charity championed by the paper.

In its editorial, the Sun called on Britons to rally behind their servicemen.

"Today we must defy the extremists and stand shoulder-to-shoulder with our armed services," it said.

"We must show our support in words and in actions. And if you see a soldier today, shake them by the hand and say thank you," it urged.

The Daily Telegraph's editorial backed Prime Minister David Cameron's assertion that the country would "never buckle" to terrorists.

"One of the most welcome developments in recent years has been the rebuilding of the connections between our soldiers and the citizens they protect," it said.

"If it transpires that Islamist terrorists have indeed taken a grisly revenge for Britain's involvement in Iraq and Afghanistan, there will need to be an urgent review of current security arrangements for all military personnel.

"But we should also remember that the Prime Minister is right. Britain's enemies, both within and without, want to destroy not just our lives but our values - including our pride in and support for the Armed Forces. And that is something they will never do," it concluded.