Cops are turning away from proactive policing after high-profile shootings of unarmed black men led to a wave of anti-police sentiment, the FBI has reported.

The bureau, which looked at the slayings of officers in 50 incidents last year, said cops are now 'scared', 'demoralized' and frightened to do their duty because they worry about being filmed by witnesses.

That has led to suspects becoming more likely to fight back, putting the cops' lives at risk, the report - obtained by The Washington Times - claimed.

Scared: Police are now scared to do their jobs after years of growing anti-cop sentiment following high-profile shootings of unarmed black men, an FBI report says. Pictured: An activist in Baton Rouge protesting police in 2016

Shot: Alton Sterling (left) was shot despite being unarmed and restrained in 2016. Michael Brown (right) was unarmed when he was shot in 2014. Both were high-profile deaths

The report claimed that police are less inclined to interact with communities or perform 'pretext stops' - in which cars are searched for drugs or guns on the pretext of a minor traffic violation - making them purely reactive.

Some refused to fight back even when being beaten up, for fear of how it might look in the media, it claimed.

The FBI looked at 50 of the 53 incidents of fatal violence against cops last year; the others were excluded because they involved minors or unknown perpetrators.

It found that a just under a third of the killers were motivated by a desire to 'kill law enforcement' - as in the deadly attacks against police in Dallas and Baton Rouge.

All of them said they were distrustful of police due to their own experiences and a string of reports of killings of black men by white cops.

Disquiet: The blowback from protesters like these (seen in 2014) - and the filming of fatal cop shootings - has led to police feeling victimized and scared to use force, the FBI report said

The apparent wave of disquiet against police began with the fatal shooting of unarmed black teen Michael Brown in 2014, the report said.

The belief - discredited by authorities - that Brown, 18, had his hands up when he was shot inspired the Black Lives Matter chant 'Hands up, don't shoot.'

Frustration escalated with a string of shootings of unarmed black men last year, including Alton Sterling, who was shot in the back despite being held down by two white cops at the time, the report said.

The high-profile nature of the killings, many of which were filmed by bystanders, also led to police being afraid to fight back when confronted with violence, it said.

The report cited one officer who was thrown to the floor and beaten by an assailant, but refused to shoot because he feared for how it might look.

The cop told their boss they 'chose not to shoot because [they] didn't want his/her "family or department to have to go through the scrutiny the next day on the national news,"' the study said.

Fear: Frightened cops are less likely to interact with communities, stop suspicious cars or do other pro-active policing, the FBI said. Pictured: cops in Ferguson, 2014, after Brown's death

Just as damaging to police confidence was a belief that politicians were no longer standing by them in the wake of Brown's shooting, it was claimed.

'Nearly every police official interviewed agreed that for the first time, law enforcement not only felt that their national political leaders [publicly] stood against them, but also that the politicians' words and actions signified that disrespect to law enforcement was acceptable,' the FBI said.

That in turn led to a belief among police that assailants were now feeling empowered to 'question, resist and fight law enforcement'.

It added that cops 'believe that defiance and hostility displayed by assailants toward law enforcement appears to be the new norm.'

The report also pointed the finger at decriminalization and lowered penalties for drug convictions, leading to a 'turnstile justice system' which is 'releasing criminals at a faster and faster pace.'

That leads to the belief 'that consequences no longer exist for criminal acts, especially drug offenses,' the report claims.

As a result, 'assailants with a history of drug offenses were more prone to be non-compliant while under the influence,' it said.

Much of the report was based on the beliefs and observations of police officers rather than concrete data.