Rising numbers of domestic abuse suspects are being released without restrictions after a steep fall in the use of police bail, a watchdog has revealed.

An inspection report raised concerns that the trend – linked to Government reforms to the pre-charge bail regime – could be leaving victims at risk of further harm.

The number of people released on all types of bail for domestic abuse crimes has dropped “considerably”, by nearly two-thirds (65%), according to Her Majesty’s Inspectorate of Constabulary and Fire & Rescue Services (HMICFRS).

The assessment warned that the reduction could be having a “detrimental effect” on victims of domestic abuse.

In more cases, bail conditions are not being used to safeguard victims, the report said.

Police are instead releasing suspects “under investigation”, meaning they are not subject to curbs such as a ban on contacting the alleged victim.

Inspector Zoe Billingham said she was concerned that changes to the use of pre-charge bail “could be making it easier for perpetrators to return to the abusive relationship, with more being released under investigation and not having bail conditions set, exposing victims to further potential harm”.

Some officers have been advising victims to apply for non-molestation orders in cases where they have not used bail, placing the responsibility on the victim to protect themselves, according to a focus group held by the inspectorate.

It was also told that suspects released with no bail conditions have returned to the family home.

New rules that took effect in 2017 introduced a 28-day limit on how long someone can be kept on police bail, with extensions requiring the approval of a senior officer and then a magistrate.

Ministers brought forward the changes amid concern over people being held on bail for months before learning they had been cleared.

Previously published figures suggest the reduction in the use of pre-charge bail has been seen across all offence types.

Last year another watchdog warned police were squandering opportunities to check DNA and fingerprints against unsolved crimes as they increasingly quiz potential suspects without arresting them.

Diana Fawcett, chief officer at charity Victim Support, said it has “serious concerns” about the increase in alleged perpetrators being released without bail conditions.

She said: “This is putting vulnerable people in danger and is an issue that requires immediate attention.”

In other findings, HMICFRS said:

– The number of arrests for domestic abuse-related crimes fell in 23 force areas, despite the overall number of offences increasing

– The charge rate for domestic abuse crimes in England and Wales has continued to fall

– Police are sometimes too slow getting to domestic abuse incidents, with a small number of delays because forces do not have enough officers available

– In one force area, the wait time between an appointment being scheduled and an officer attending was up to 16 days

Overall, HMICFRS found continued improvement in how police identify, respond to and support domestic abuse victims.

Ms Billingham added: “There’s no question that police forces have come a very long way in responding to victims of domestic abuse – victims are now better supported and better protected.”

An estimated 1.9 million adults aged 16 to 59 experienced domestic abuse in the 12 months ending March 2017, according to the Crime Survey for England and Wales.

The offending results in social and economic costs of at least £66 billion a year, the Home Office estimates.

National Police Chiefs’ Council lead for domestic abuse Deputy Chief Constable Louisa Rolfe said the report highlights “substantial progress” made by forces.

She added: “Domestic abuse is an increasing proportion of emergency call-demand in every force at a time when resources are stretched, and so our ability to provide the best response to victims is affected.

“The reduction in the proportion of suspects being bailed following arrest came after new legislation to change the way pre-charge bail is used. We are continuing to review the impact of these changes, particularly on the most vulnerable people, like victims of domestic abuse.”

The Home Office said pre-charge bail can be used whenever it is necessary and proportionate and such decisions are “operational matters” for police.

A spokesman said: “We are determined to ensure anyone facing the threat of domestic abuse has somewhere to turn to.

“We have been encouraged by the significant improvements in the police response to domestic abuse, with prosecutions and convictions up by 20% and 28% respectively.”

Last month, the Government published a Domestic Abuse Bill containing a number of measures aimed at boosting support for victims and tackling perpetrators.