By Natalie Bloomer and Samir Jeraj

Sadiq Khan has been urged to rethink his position on victims of crime being handed over to the Home Office for immigration enforcement, after he said that police officers were "duty bound" to report them.

The practice, which was revealed by in April, has been slammed by migrant groups over fears that it could deter victims from reporting incidents to the authorities.

When asked about the issue by Green party London Assembly member Sian Berry, Khan said that police officers were "duty bound" to report victims of crime to the Home Office if there were "reasonable grounds" to suspect immigration offences.

Berry went on to ask whether the mayor was concerned that vulnerable people in London may not be reporting serious crimes because they fear deportation. He didn't respond to this and instead referred her to his previous response.

The human rights organisation Amnesty UK has now called on Khan to rethink his position. The director of the group's Refugee and Migrant Rights programme Steve Valdez-Symonds said:

"Amnesty urges the London mayor to reconsider his position. We must not allow the UK to be a country in which many people cannot trust public services, including the police, to help and protect them or their loved ones because they fear being reported to immigration authorities.

"When victims of domestic violence, human trafficking and other crimes are too afraid to seek help, they and their family are even more easily preyed upon by individual abusers and organised criminals."

The director of the Migrants' Rights Network Fizza Qureshi said Khan's response was "extremely disappointing".

"It is extremely disappointing to hear the mayor's response to this issue," she said. "This will deter marginalised and vulnerable individuals, like victims of trafficking or exploitation, from approaching the police.

"His position also undermines any strategies he is undertaking of inclusion, community cohesion, and integration of London's communities. If we want London to be a truly safe and inclusive city for everyone, and for victims of crime to come forward, then we would call on the mayor to support the removal of any reporting requirements between the police and the Home Office."

Sian Berry told that she would seek clarification about the precise meaning of the phrase "reasonable grounds" and what guidance police officers are given in relation to this.

"I was very disappointed that mayor didn't answer my questions fully. As it stands, it sounds as if people reporting crimes are automatically being turned into suspects. This will drive more and more people into danger. There needs to be a safety wall between police and immigration enforcement."

A mayoral spokesperson said:

"All victims of crime in the capital are entitled to help and support through a range of statutory and voluntary services, regardless of their immigration status. Cases are individually assessed by the Met, with the needs of the victim being the police's primary focus, and only in cases where officers have reasonable grounds to suspect an immigration offence has been committed would it be reported to the Home Office because it has to be by law."