THE police watchdog the IOPC has confirmed it will investigate "any interaction" between police and two teenagers who died in a crash in Cardiff on Monday.

The boys, aged 15 and 16, were riding an electric bike when they were involved in the fatal crash in Ely.

Later that evening, as officers examined the scene, "large scale disorder" erupted in the neighbourhood, with reports of crowds of youths clashing with riot police.

South Wales Police referred the incident to the IOPC (Independent Office for Police Conduct) and after reviewing the case, the watchdog has decided to investigate.

South Wales Argus: A car set alight and a damaged police car in Ely, Cardiff, as rioters clashed with police.A car set alight and a damaged police car in Ely, Cardiff, as rioters clashed with police. (Image: Bronwen Weatherby/PA Wire)

"Following a referral from South Wales Police we have decided to independently investigate an incident in Ely, Cardiff, on Monday which resulted in the deaths of two teenagers," the IOPC said in a statement today, Wednesday.

"Our decision to investigate follows our attendance at the police post incident procedure and after a review of the information received to date.

"We will be examining any interaction between the police and the boys after CCTV footage emerged apparently showing a police vehicle following a bike prior to the incident."

IOPC director David Ford added: "First and foremost our thoughts and sympathies go out to the families and friends of the two boys who sadly lost their lives on Monday evening in Ely.

"It is important that we independently investigate the circumstances leading up to this tragic event.

"This incident and the events that followed have, understandably, attracted significant interest and public concern.

"It is important that we thoroughly and independently investigate this matter, in order to establish the full facts and circumstances of exactly what happened on Monday."

South Wales Argus: Flowers and tributes left for the two teenagers in Ely, Cardiff, whose death in a car crash sparked a riot.Flowers and tributes left for the two teenagers in Ely, Cardiff, whose death in a car crash sparked a riot. (Image: PA Wire)

Hundreds of bunches of flowers have now been placed at the scene of the fatal crash in Ely where Kyrees Sullivan, 16, and Harvey Evans, 15, died.

Community members and young people continue to gather at the scene and say there is still a strong feeling of anger at the police among those who knew the teenagers and their families.

South Wales Police have said they are investigating claims of a pursuit but said the collision had already happened when the first officers arrived on the scene.

Additional reporting by PA Media.