Gunman Jake Davison had his shotgun and certificate seized after concerns were raised following an assault on two youths, a police watchdog has said.

They were returned to him in July after a police review once he had completed a rehabilitation scheme, the Independent Office for Police Conduct (IOPC) said.

A worker on the scheme had raised concerns over Davison’s shotgun ownership, leading to the seizure.

Davison, 22, shot and killed five people in Plymouth on 12 August.

He killed Maxine Davison, 51, Stephen Washington, 59, Kate Shepherd, 66, Lee Martyn, 43, and three-year-old Sophie Martyn, before turning the gun on himself in Keyham.

Davison had been placed on the rehabilitation scheme after admitting the previous assault on the two youths, which took place last September.

The IOPC said the shotgun certificate was then reviewed once Davison had completed the Pathfinder scheme, which aims to “reduce harm and reoffending”, in March this year.

The programme is “designed to deal with offenders outside of the criminal justice system” by deferring charges and cautions.

Following the review by Devon and Cornwall Police’s firearms licensing department, the shotgun and certificate were returned to Davison on 9 July.

The IOPC is investigating the decision to return them.

His certificate was originally issued for sporting purposes in July 2017 and was valid for five years.

Devon and Cornwall Police Chief Constable Shaun Sawyer said Jake Davison was permitted to use a gun for clay pigeon shooting.

Mr Sawyer said it was “extremely rare” for licensed guns to be misused in this way in the UK.

A review is to be held into Devon and Cornwall Police’s firearms procedures.

Speaking to the BBC, Mr Sawyer said: “I understand the unease. This was a licensed firearm that Jake had, I absolutely accept that.

“I’d ask people to reflect that those firearms, in my 10 years as chief constable, have never been used in that way.

“This is unprecedented for us in Devon and Cornwall and the city of Plymouth.”

However, Mr Sawyer said firearms were “part of a rural economy and we have to accept that”.

He said: “They’re heavily regulated, they’re heavily reviewed, and that’s really important for public safety because it’s the only thing police regulate that’s designed to take life.”

When asked about future changes, Mr Sawyer said he believed new guidance from the Home Office would see social media checks become a “must” for police forces, rather than a discretionary decision based on the applicant.

“I think we have to realise it will be hard to monitor, but if that’s where society wants to go, then that’s where we’ll go,” he said.

All police forces across England and Wales have been asked by the government to review their current firearms processes following the tragedy.

The chief constable said he had not been asked to step down, but would reflect on his position “once we have the facts”.

“As a man and a father and a parent, a child has lost its life on my watch, through a mechanism that is licensed by me,” he said.

He paid tribute to the people of Keyham, where the shootings happened, for their “dignity and strength of fortitude” which had “helped to stabilise the city”.

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