The State Department's annual 2006 report on human trafficking around the world notes some progress on the issue last year, although it says the overall situation for what it calls "modern slavery" is still bad.
The report also warns Germany over an influx of women being brought into the country to serve as prostitutes during the World Cup.
In introducing this year's congressionally mandated report, Secretary of State Condoleezza Rice said an estimated 800,000 people, mostly women and children, are victims of human trafficking.
"The harsh reality of human trafficking stuns even the hardest of hearts - stories of the sexual exploitation of young girls, stories of men and women toiling as slave labor in sweatshops, stories of children forced to kill as rebel soldiers. Defeating human trafficking is a great moral calling of our time."
This year's report lists Belize, Burma, Cuba, Iran, Laos, North Korea, Saudi Arabia, Sudan, Syria, Uzbekistan, Venezuela and Zimbabwe as countries where governments fail to take effective action to combat human trafficking.
The State Department's John Miller said there is no way to definitively count the number of human trafficking victims around the world. But, he said an increase in the number of arrests of traffickers is, in his words, "the start of progress."
"While several years ago, there were just hundreds of traffickers, last year there were about three-thousand convictions of traffickers worldwide. This year, it's up to around 47,00. That is sending a message, or more of a message anyway, and that is a good sign."
One issue addressed in the report is labor trafficking in Iraq. Miller said the Pentagon investigated a recent case involving Nepalese workers, and has adopted new regulations as a result.
"One, that any contractor that's responsible to see that workers had their passports. This is a very common technique of the traffickers, grab the passports. That all contractors and sub-contractors had to have a signed copy of the employment
contract. That subcontractors and contractors must be licensed recruiting firms. And that recruiting firms not charge employees illegal recruitment fees."
Meanwhile, the U.S. official said Washington is troubled by the apparent export of workers from North Korea to other countries.
"We are concerned that there are reports from both the Czech Republic and Mongolia, for example, of North Korean workers being held in those countries, doing work. The conditions may be better than in North Korea, but they are still - the
reports are - they are still trafficking victims. They lack freedom. It's not clear they get any money, whether the money goes to them or the North Korean government."
He added that Washington is concerned about North Koreans who are trafficked in China.
"And some of these are trafficked into China, and some of them are trafficked after they get to China, a lot of them are trafficked to be brides, filling this imbalance that comes from this one-child policy."
Miller said there is special attention being paid to Germany, even though the report gives the country its highest overall rating for compliance with efforts to stop trafficking.
The U.S. official said there are reports thousands of women are being transported to Germany to serve as prostitutes during the World Cup. He said the German ambassador to the United States has assured him that the government is taking measures to stop trafficking.