Brussels warned European Union nations Monday to get a move on with adopting tough new rules against human trafficking or face sanctions as a first report on the problem showed "modern-day slavery" worsening across the bloc.

The report signalled an 18 percent increase from 2008 to 2010 in identified and presumed victims of trafficking in the 27-nation EU, with the total at 23,632.

"This is the sad truth," said Home Affairs Commissioner Cecilia Malmstroem. "Men, women and children are being sold for sex, hard labour ... forced into marriages, domestic servitude, begging, or have their organs removed for trade."

"What we know is just the tip of the iceberg," she added.

A study by the International Labour Organisation last June estimated that 880,000 people were in forced labour in the EU, a problem expected to worsen as the economy fails to pick up and employers seek ever cheaper labour.

Though the EU report showed fewer thrown behind bars during the same period—with convictions declining 13 percent—most member states had failed to implement a tough new package of rules agreed last year, she said.

Only six of the EU-27 had transposed the EU rules into national legislation despite an April 6, 2013 deadline—, Finland, Latvia, Hungary, Poland, Sweden—with Belgium, Lithuania and Slovenia partially in line.

"It is for member states to stop dragging their feet," Malmstroem said, calling for states to implement "without delay" the Anti-Trafficking Directive.

"I will not hesitate to take the necessary measures to ensure that this is being done," she added.

Europe two years ago agreed to toughen up against the booming trade in human beings, estimated at an annual 2.5 billion euros ($3.3 billion), by broadening the definition of the crime—from sexual exploitation and slave labour, to forced begging and removal of organs—and setting harsher penalties.

Monday's EU report showed seven out of 10 victims to be women, 17 percent men, 12 percent girls and three percent boys.

More than half of the victims—61 percent—were from EU nations, most often Romania and Bulgaria, with Nigeria and China as the most common countries of origin outside Europe.

The majority of the victims were trafficked for sexual exploitation, at 62 percent, with trafficking for forced labour second at 25 percent and trafficking for the removal of organs, for criminal activities or for the selling of children accounting for the remainder.

The new rules set maximum penalties of at least five years behind bars, with 10 for "aggravating circumstances"—if the offence is against a child or with serious violence, or involves a crime ring.

The regulations also enable nations to take judicial action outside its territory in a case where an offence is committed against one of its nationals or residents.

In a 2010 report, the UN Office on Drugs and Crime described as "one of the most lucrative illicit businesses in Europe", estimating gains through and forced labour alone at around 2.5 billion euros per year.

European lawmakers have said the trafficking business is second-only in illegal activity to the weapons trade—more even than drugs—with the risk for people involved "fairly low" until now.