A Sussex Police spokesperson said, “Emergency services responded to the incident after the 27-year-old man, who was in the road, sustained serious injuries after colliding with the marked police vehicle near the junction of Dorothy Avenue.
“Despite the best efforts of paramedics and responders, he died at the scene.”
Officers said as the incident involved a police vehicle, the matter has been referred to the Independent Office for Police Conduct (IOPC) which will carry out an independent investigation.
The spokesperson said a closure with the junction of Bramber Avenue remains in place.
Chief superintendent Jo Banks said, “This is a tragic incident and we are fully supporting the IOPC investigation.
“We want to thank drivers and residents for their patience while the A259 South Coast Road was closed.”
Police are urging anyone with information or dash cam footage of the incident to email [email protected] quoting Operation Ambleside.