Two police officers in a marked van who followed two teenage boys on an electric bike before it crashed killing them both have been served with gross misconduct notices.

Harvey Evans, 15, and 16-year-old Kyrees Sullivan, who had been "best friends" since they were young children, lost their lives after a crash in Ely, Cardiff last month.

The officers, who were driver and passenger in a marked police van, have been identified after analysis of CCTV footage of the car driving behind the boys’ electric bike a short time prior to the fatal collision.

"As part of our investigation, we have served gross misconduct notices on two police officers, the driver and passenger in a marked police van, which was seen on CCTV footage driving behind the boys’ electric bike a short time prior to the fatal collision on May 22," a spokesperson for watchdog Independent Office for Police Conduct (IOPC) said

“Such notices advise officers their conduct is subject to investigation. They do not necessarily mean that any disciplinary proceedings will follow.

“Our investigation began last month following a referral from South Wales Police, after relevant CCTV footage came to light."

Days after the deaths approximately one thousand people lined streets in Cardiff in tribute to Harvey and Kyrees.

Following the collision, tensions reached breaking point as several vehicles were set alight, property was damaged and police officers were injured in a riot in the area.

Kyrees' mother, Belinda, had claimed police officers "killed her son" in the wake of tragedy.

But IOPC continues to investigate the circumstances of the tragedy.

he watchdog continued: “Investigators are reviewing hundreds of video footage clips that we have gathered as a result of our house-to-house enquiries and leafleting at properties in Ely.

“To ensure we identify and secure relevant evidence, we have followed up inquiries with, and taken statements from, some local residents.

“We have also set up witness appeal boards on relevant streets. In addition to these lines of inquiry, we have reviewed initial accounts and body-worn video from relevant police officers and staff.

“We are in regular contact with the families of Kyrees Sullivan and Harvey Evans, who sadly lost their lives, to keep them updated on the progress of our investigation.

“Our investigation continues to focus on the nature of the police interaction with the two boys prior to the collision and the appropriateness of the officers’ decisions and actions.

“In particular, we are examining whether at any time the decisions and actions of the officers in the police vehicle constituted a pursuit. South Wales Police has continued to co-operate with our investigatioN.

When dozens of rioters clashed with police after the deaths, objects were hurled at officers.

IOPC says the community has helped the watchdog and it may still need to talk to other residents in Ely, a district in the west of the city.

IOPC Director David Ford: "I wish to again extend my sympathies to the family and friends of Kyrees and Harvey, and to everyone who has felt the impactful loss of two young lives in Ely. The response from the community in helping our investigators has been very positive and I am extremely grateful for this assistance.

"In case there are still people with relevant information we have yet to speak to, we have placed witness appeal boards in the vicinity of the incident. We would urge anyone who believes they have useful information to come forward to us. We have also met with local community leaders and elected officials to explain our role and the remit of our investigation.

"As our investigation continues to progress, I would like to reassure everyone that we are focussed on establishing precisely what happened in the run up to the tragic incident. Our work will remain impartial and completely independent of the police."

A South Wales Police spokesperson said: "On Monday, June 12, investigators from the Independent Office for Police Conduct (IOPC) served gross misconduct notices on two South Wales Police officers as part of its investigation following the deaths of Kyrees Sullivan and Harvey Evans in Ely on May 22.

"The serving of a gross misconduct notice does not necessarily mean an officer has committed any wrongdoing. It is to notify an officer that their conduct is being investigated.

"The force continues to fully co-operate with the IOPC investigation and is providing them with information and material, including CCTV footage and body-worn video.

"We acknowledge the impact Kyrees Sullivan’s and Harvey Evans’ deaths have had on their families, friends and the wider community. Our thoughts and condolences continue to be with them."