The United Nations official in charge of anti-trafficking efforts has urged the government of Thailand to do more to combat human trafficking and protect the rights of migrant workers.

Joy Ngozi Ezeilo said Monday in Bangkok that Thailand faces significant challenges as a source, transit and destination country for trafficked people. She expressed her concerns after a 12-day mission to Thailand, which ended Friday.

Ezeilo said the trend in trafficking for forced labor is growing in scale in Thai agricultural, construction and fishing industries. She also found that internal trafficking and exploitation of children is rampant, and that migrant, stateless and refugee children, including those belonging to hill tribes are especially vulnerable.

The U.N. expert said the enactment of a 2008 anti-trafficking law is in line with international standards, but its implementation remains weak, often due to corrupt officials. She urged the Thai government to promote zero tolerance for corruption, especially among the law enforcement officers, immigration officials and labor inspectors.

A full report of Ezeilo's mission will be submitted to the United Nations Human Rights Council in June 2012.