Image caption The five knives delivered by Amazon

Tesco and Argos have been breaking the law by selling knives to 16-year-olds without making proper ID checks, a BBC investigation has found.

A 16-year-old actress, sent by BBC Watchdog, was able to buy a kitchen knife that it is illegal to sell to someone under 18 in Tesco and Argos.

Amazon broke its own delivery rules by handing over four knives ordered by the programme to the girl and leaving another one in a bin.

The firms said they will investigate.

In all, the teenager visited five different branches of Wilko, Asda, TK Maxx, Tesco and Argos.

In Tesco, the UK's biggest supermarket, the teenage actress was sold a knife in three of the five stores that she visited, while one Argos store sold her a knife with no ID being checked.

Four of the knives ordered from Amazon were delivered into her hands and one was left in a bin, rather than following the company's policy and refusing to hand them over to the teenager.

No branches of Wilko, Asda and TK Maxx sold a knife to the 16-year-old.

All of the retailers have signed up to a voluntary code in 2018, committing to check the ID of anyone they suspect of being under either 21 or 25 before selling or delivering a knife to them.

Stephen Knight, from London Trading Standards, said of the Tesco sales: "The fact that in three different stores we managed to get a purchase shows a more systematic issue about that particular organisation, not rolling out effective training procedures to staff."

He added that the knife sold in Argos was "an unlawful sale to a young person" and "shouldn't have happened".

When presented with the findings, the companies promised to act:

Tesco said: "The responsible sale of knives is something we take very seriously and so we are disappointed to learn of the results of Watchdog's tests and we apologise for this." The company said it provided staff training to prevent knives being sold to underage buyers and made unannounced test purchases. Tesco said it would be "reiterating these protocols and highlighting their importance in the stores tested in the investigation".

Argos said it had "clear responsibilities as a retailer and operated a strict "Think 25 policy" our colleagues are trained to enforce". It is also looking into why the process was not followed here.

Amazon said: "Drivers undergo training in age verification delivery, regular audits monitor compliance and if drivers fail to follow our guidelines they will face action which can include no longer delivering orders to our customers."

Knife crime in England and Wales rose to record levels last year, data shows.

Police recorded 40,829 offences involving knives or sharp instruments in 2018, up 6% on the year before.

The Office for National Statistics said cases of murder and manslaughter, excluding terror attacks, increased by 12%. There were 732 killings, up from 655 in 2017 - the highest since 2007.

'My heart and soul'

On 3 July 2017, Alex Leonard was asleep at home when he was woken by someone outside kicking his car.

Alex went to confront the individual, who pulled out a knife and stabbed him through the chest. His murderer was 16 years old.

Image caption Debbie Leonard said her son Alex was "full of life"

Alex's mum Debbie Leonard, who was on holiday at the time, told BBC Watchdog Live that her son was "full of life, full of laughter and he was my heart and soul".

She said: "I was so happy in my bubble, my little bubble of a life, and then my bubble got stabbed and it has burst open and now I am wandering lost, I feel so lost.

"This is happening so much, this escalation, because everyone is carrying a knife."

'Easily obtainable'

Duncan Ball, knife crime lead at the National Police Chiefs Council, said: "For me, finding out that the young person has been able to purchase knives is very concerning.

"The figures that you mention are exactly in line from our own findings and broadly we find that about a fifth to a quarter of stores do supply to young people.

"Predominantly we see knives that are easily obtainable, so in the main it is indeed kitchen knives."

You can watch the full investigation on Wednesday 8 May at 20:00 BST on BBC One or on iPlayer afterwards.