London - Police arrested nine men in northern England suspected of trafficking and raping young women following raids on Tuesday on several homes in a crackdown involving more than 150 officers.

The arrests were made in the town of Stockton and city of Sheffield as part of a major ongoing investigation into the sex abuse, exploitation and trafficking of women across Britain, according to Cleveland police force, based in northeast England.

The raids were carried out after officers received intelligence that at least 10 women were trafficked both within the region and across the country, and raped by multiple men in various addresses over a period of several months, police said.

The number of officers involved - more than 150 - was "exceptionally high" for an anti-trafficking operation, Will Green, a police spokesman, told the Thomson Reuters Foundation.

Police forces across the country are ramping up efforts to investigate cases of trafficking and modern slavery, with more than 500 live policing operations into the crimes ongoing, say the National Crime Agency (NCA) - dubbed Britain's FBI.

"Our message is clear, to those who are victims of this vile abuse; there is hope," said Jason Harwin, Cleveland police assistant chief constable.

"We are on your side; we can and will help you."

At least 13,000 people across Britain are estimated by the government to be victims of modern slavery - but police say the real figure is far more likely to be in the tens of thousands.

"Human trafficking, the exploitation of the most vulnerable in our communities by the most ruthless, will not be accepted," Harwin said in a statement following the arrests.

Police recorded 2,255 modern slavery crimes in the past financial year - up from 870 cases during the same period for 2015/16 - according to Britain's anti-slavery tsar Kevin Hyland.

In September, nine members of a British family who enslaved vulnerable adults while enjoying a lavish lifestyle were sentenced to a total of almost 80 years in prison following one of the largest investigations of its kind in the country.

Despite the upsurge in cases, police in Britain are failing slaves, with a lack of understanding, mediocre investigations and troubling attitudes from officers leaving many victims prey to further exploitation, a police watchdog said in October. 

Thomson Reuters Foundation