A suspected sex trafficker of young girls and a convicted rapist are among five foreign nationals feared to be hiding in west London.
The Metropolitan Police's Extradition Unit is hunting a total of 17 “dangerous” men, wanted by authorities across Europe, as part of Operation Sunfire.
Most have links to London, but “extensive police enquiries” have yet to reveal their whereabouts, the Met said, warning: "It may be that they live next door to you."
One of those being sought is Romanian national Balint Budi, 25, who is wanted by Romanian authorities in connection with human trafficking.
Detectives investigating the organised sexual exploitation of girls aged 12 to 17 in Brasov, Romania, between February and March 2010, want to speak to him.
The Met warned he has previous links to Brent and may still be in the area.
Polish national Tomasz Naumowicz, 33, is wanted by authorities in his home country, having been convicted of rape.
He is due to serve five years for the violent rape of a woman in Zdunska Wola, Poland. On the evening of September 20, 2008, Naumowicz physically restrained the woman, threatened to stab her to death and raped her.
He has previous links to Hounslow and Richmond.
Patryk Kokoryk, 33, is wanted by Polish authorities to serve a jail term for a violent attack.
On October 3, 2010, he and an associate beat their victim's chest and legs with a table leg in Lublin, Poland. Kokoryk was sentenced to eight months imprisonment on January 12, 2012.
Albanian Abri Bucpapaj, 35, is wanted in connection with allegations of rape, assault and threats to kill.
Finnish officers are investigating three allegations of assault against a child and a woman, the rape of a woman and threats to kill the woman and a man, in Oulu, Finland, between July 2010 and November 2011.
They want to speak to the Albanian national, who officers believe may be in Harrow, Barnet or Brent.
Tomasz Pieta, 31, is wanted by Polish authorities, having been convicted of robbery, assaulting a police officer and criminal damage.
Pieta was convicted of seven offences and is due to serve three years, eight months and 18 days in jail.
Between 2001 and 2006, Pieta assaulted three men, before stealing their valuables in most cases. On February 27, 2006, he and two others also punched a police officer in the face.
Pieta's conviction also includes the burglary and criminal damage of a summer house.
Officers suspect he is in west London, although he is believed to have particular links to the Wembley area.
This is the fourth time the Extradition Unit has run Operation Sunfire.
Almost half of those wanted in previous appeals have subsequently been arrested. A total of 20 out of 42 men and women considered dangerous were arrested by the Extradition Unit and authorities overseas.
Detective Sergeant Peter Rance, of the Met's Extradition Unit, is leading Operation Sunfire 4.
He said: "We believe that these people are dangerous, so taking them out of our communities and putting them before the courts is of paramount importance.
"I urge the public to look closely at these pictures. Do you recognise these men? It may be that they live next door to you, or you see them regularly elsewhere in your community.
"If you have information on their whereabouts, please tell Crimestoppers, so that we can arrest them. If you see them, call 999 and do not approach them.
"The Met is committed to arresting dangerous criminals - whether they are British or foreign nationals. We conduct extensive enquiries on a daily basis, however, experience tells us that co-ordinated operations such as Sunfire encourage the public to provide us with the information that often leads to arrests."
Anyone with information should call Crimestoppers, anonymously, on 0800 555 111.