An investigation has begun after the death of a woman who was found "unconscious and unresponsive" in a police cell in Bradford city centre.

Claire Harper, 41, was detained by West Yorkshire Police early on Sunday morning and was being held at Trafalgar House, the force’s main Bradford police station on Nelson Street.

In the early afternoon, she was found unconscious in her cell and rushed to hospital, but doctors were unable to revive her.

Her death was announced yesterday.

The incident is now being investigated by the new police watchdog, the Independent Office for Police Conduct (IOPC).

It will be one of the first investigations carried out by the watchdog, which only came into being on Monday, replacing the Independent Police Complaints Commission.

The IOPC described Miss Harper’s death as a “tragic” and “serious” incident and is now looking at the interactions between her and the police in the hours leading up to her death.

It is also liaising with her family.

A statement from the IOPC said: “Miss Harper was detained in the early hours of Sunday morning (January 7 2018) and was being held at Trafalgar House, Bradford.

“At around 12:30pm she was found unconscious and unresponsive in her custody cell.

“An ambulance was called and Miss Harper was transferred to Bradford Royal Infirmary, but could not be revived.

“Investigators from the Independent Office for Police Conduct attended the custody suite and looked at the post incident procedures on Sunday.

“Since then they have been carrying out their initial evidence gathering.”

Neither the IOPC nor West Yorkshire Police have revealed details of the reasons for Miss Harper’s initial arrest.

An inquest to determine the cause of her death has yet to be opened by the coroner’s office.

IOPC Operations Manager Catherine Bates said: “We would like to offer our sympathies to Claire’s family and friends and everyone affected by this tragic incident.

“We have been in contact with Claire’s family to keep them informed and provide them with our support during this difficult time.

“Whenever someone dies following contact with the police, it is automatically referred to us.

“This is a very serious incident and we will be investigating the contact West Yorkshire Police had with Claire prior to her death.”

The Telegraph & Argus asked the IOPC how long the investigation might take, but a spokesman said that there was, as of yet, no timetable.

Imran Hussain, MP for Bradford East, the constituency Trafalgar House is based in, said: “This is of course an extremely sad case and my thoughts and prayers go out to Claire’s friends and family at this difficult time, and the new Independent Office for Police Conduct must fully investigate what led to this tragic incident.”

The IOPC was only launched on Monday, replacing the IPCC as the body which oversees the police complaints system in England and Wales. It investigates deaths of individuals following police contact, including deaths in custody and fatalities following police chases.

It also deals with complaints against bodies including the Home Office, National Crime Agency and HM Revenue and Customs. It was set up following criticism of the IPCC’s independence and powers by the families of several people who had died in police custody. The new watchdog will make decisions independently of the police and government, and neither its Director General nor its directors have worked for the police. It can start its own investigations without having to wait for police refer a case, reopen probes where new evidence emerges and investigate disciplinary claims against chief officers.