More than 42,000 adults and children were found in forced prostitution, labor, slavery or armed conflict in 2011, a US government report has found.

Some 9,000 more victims were identified around the world than in 2010, the state department report said.

But the number is just a fraction of the estimated 800,000 people trafficked across borders every year.

Conflict-wracked Syria was relegated to the category of worst offenders, while seven other states came off that list.

Syria's Middle Eastern neighbor Lebanon and Burma were among those judged to have improved their efforts to combat what the state department terms "modern-day slavery".

Syria was identified as a transit country for Iraqi women and girls, South East Asians and East Africans being trafficked for a life of prostitution in Europe, the Trafficking in Persons (TIP) report said.

In addition, thousands of women from several nations have been left working as forced domestic servants inside Syria as the conflict escalates.

At least 95 Filipina women remained trapped inside the cities of Homs and Hama at the end of 2011, the International Organization for Migration said.

Syria's government was making "no discernible effort" to identify and protect victims of trafficking, the report said, and could now be subject to US sanctions for dropping into the bottom tier.

The report ranks each of the world's nations for their compliance with US and global anti-trafficking laws.

Those laws are aimed at tackling a global trade in humanity that sees an estimated 20.9 million people living in modern-day slavery at any one time, according to a new estimate by the International Labor Organization.

Much of Western Europe and North America is regarded as "Tier 1" territory - countries whose governments fully comply with minimum standards for the elimination of trafficking.

But even top-tier nations face problems.

The US, which faces an ongoing struggle with sex traffickers smuggling women into prostitution from Mexico and Latin America, saw government funding for anti-trafficking measures drop during 2011.

More money was needed for victim support, the report said, along with improved data analysis and identification services and a push to help businesses understand how to avoid employing victims of trafficking.

The report's overall emphasis on victim support and identification would be welcomed by those working in the US and overseas, one non-governmental organization said.

"Treating victims as victims and not as criminals is important," said Bradley Myles of Polaris Project, a US-based anti-trafficking operation. "These are victims of crime with human rights and they should be protected."

'Systematic repression'

Seventeen nations - mainly in Asia and North and Sub-Saharan Africa - were placed in the lowest tier in the 2012 report.

Syria's entry to that groups places it with the likes of Cuba, Iran, North Korea and Zimbabwe in clear violation of anti-trafficking laws.

Burma climbed out of the bottom tier to a 42-nation-strong "watch list", the report said, mainly as a result of a new effort by its government to address forced labor and the conscription of child soldiers.

Lebanon made the fight against human trafficking a national priority, the report said, passing a new law that helped it climb a peg.

China and Russia remained on the "watch list", with the state department remarking that China continues to practice a "systematic form of repression" known as "re-education through labor".

Most countries on the list, 93, were ranked in Tier 2 - judged to be in breach of anti-trafficking laws but making notable efforts to end those breaches.

Among the countries promoted to Tier 1, Nicaragua made its first appearance, one that US anti-trafficking chief Luis CdeBaca said was evidence of a positive anti-trafficking trend in Latin America.