Police investigating a suspected hit-and run crash in which a 17-year-old cyclist was seriously injured are still trying to trace a man.

The boy was riding his bicycle on Banbury Road in Summertown when he was involved in a collision with a motorcycle at about 8.15am on Monday (November 4).

The cyclist sustained life-threatening injuries and remains in hospital in a serious, but stable condition.

The motorcyclist failed to stop and left the scene, police said.

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They believe Nazim Kacem, 29, from Oxford, may have "vital information" relating to the incident.

Banbury Road in Summertown was taped off on Monday (November 4) (Image: Toby Oliver)

Mr Kacem is also known to frequent Bristol and Crouch Hill in London.

Four people have so far been arrested in connection with the investigation.

A 14-year-old boy was released without charge.

Three others, a 50-year-old man, a 41-year-old man and 37-year-old woman, all from Oxford, were released while investigations continue.

Senior Investigating Officer Detective Inspector Justin Thomas of the Serious Collision Investigation Unit said: “I am appealing to anybody who knows the whereabouts of Nazim Kacem to please contact Thames Valley Police.

“We would like to speak to him as a matter of urgency in relation to this collision.

“I would also like to appeal directly to Nazim to please contact us if you see this appeal.

“You can get in touch by making a report online or by calling us on 101, quoting reference 43240532710."

Alternatively anyone who knows of Nazim’s whereabouts can also call the independent charity Crimestoppers anonymously on 0800 555 111.

Anyone who witnessed the incident or who may have dash-cam or CCTV footage that has captured the collision, or the moments leading up to it, is also asked to get in touch with Thames Valley Police.