The changes would ensure the worst perpetrators will receive a life sentence and those already with a conviction for a very serious sexual or violent offense would face an automatic life sentence, the Home Office said in a release.
The measure will be included in a Modern Slavery Bill, which will be published as a draft for a pre-Parliament review.
The bill would consolidate offenses used to prosecute slave drivers, the Home Office said. It also would create "trafficking prevention orders" that would restrict activity and movement of convicted traffickers and stop them from committing future offenses, and would create the new post of Anti-Slavery Commissioner to hold law enforcement and other organizations accountable.
An Inter-Departmental Ministerial Group on Human Trafficking report published Friday indicated 1,186 people were identified and referred for support in 2012, an increase of 25 percent in the number of referrals from 2011. The report also said trafficking primarily is a crime associated with gangs.
"Modern slavery is an appalling evil in our midst. Today's figures are unlikely to reflect the full extent of this largely hidden crime or the human suffering that lies behind each statistic," said Crime and Security Minister James Brokenshire.
The Modern Slavery Bill sends a strong message to those "involved in this disgusting trade in human beings," Brokenshire said. "[You] will be arrested, you will be prosecuted and you will be locked up."
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'
Exploding whale video goes viral on Internet