Gwent Police has vowed to co-operate fully with an investigation into the death of a 29-year-old man who died shortly after coming into contact with its officers.
Moyied Bashir suffered a "medical episode" during an incident at his home in the city last Wednesday.
Nine officers from Gwent Police attended Mr Bashir's home in response to concerns for his welfare and later called an ambulance due to his "behaviour".
Although not under arrest, Mr Bashir was handcuffed and leg restraints were applied.
When his condition was seen to deteriorate, he received medical attention and was taken to hospital where he later died.
The force referred itself to the Independent Office for Police Conduct (IOPC) because of contact with Mr Bashir prior to his death.
Independent investigators are examining body worn video, police radio transmissions and call logs.
Chief Superintendent Tom Harding, of Gwent Police, said: "Everyone at Gwent Police takes any loss of life extremely seriously and I wish to offer the family and friends of Moyied Bashir, who died this week, our sincere condolences.
"This is a tragic death. We have and will continue to co-operate fully with the investigation which the Independent Office for Police Conduct (IOPC) is carrying out.
"The IOPC was contacted promptly after Moyied Bashir's death and they quickly began their own independent investigation.
"Nine officers had responded to the incident prior to the ambulance arriving, and as a result took part in post-incident procedures which is in keeping with standard practice in such cases. This process was overseen by the IOPC."
Mr Harding said all uniformed officers wore body worn cameras and the footage from the incident has been handed over to the IOPC.
"There have been, understandably, calls from the community for us to release this footage publicly, however this footage is now owned by the IOPC and as such it is not Gwent Police's to release," he said.
"I understand that there is a high level of concern with that within our community, and we appreciate their patience in allowing the IOPC to conduct their investigation and I am confident that they understand the community's concerns and report their findings as soon as they are able.
"We will continue to co-operate fully with their investigation."
Catrin Evans, IOPC director for Wales, said: "I offer my condolences to Mr Bashir's family and friends, and to everyone affected by his tragic death.
"We have spoken to family members to explain our role and how the investigation will progress.
"It is appropriate in the circumstances of a death following police contact that we investigate what happened, and I would like to reassure people that we will do so thoroughly and independently.
"We will be carefully examining the interaction police officers had with Mr Bashir and whether their actions were proportionate and reasonable in the circumstances."
Mr Bashir's death last week prompted a protest that began in the city centre before marching on Newport Central Police Station.
A GoFundMe page set up by Mr Bashir's brother, Mohamed Bashir, has raised more than £7,000 for his funeral.