The government is facing criticism from some quarters that border controls are too weak, while others say people seeking asylum are being treated inhumanely.

The truck, carrying migrants from Mexico, Guatemala, Honduras and El Salvador, was discovered abandoned in a desolate, industrial area near a highway about 160 miles north of the US-Mexico border.

The US Department of State says Malaysia does not fully meet the minimum standards for the elimination of trafficking and is not making significant efforts to do so.

Officials described finding the trailer's rear door ajar with bodies stacked inside that were hot to the touch.

If convicted each man faces a maximum sentence of life in prison, or possibly the death penalty, the US Justice Department says.

The grim discovery is one of the worst disasters involving migrants in the US in recent years.

Human Resources Minister M Saravanan says this will only encourage more undocumented migrants to enter the country.

Negeri Sembilan mufti Mohd Yusof Ahmad says Islam demands that its followers treat everyone fairly without considering their backgrounds.

The Malaysian Employers Federation says short-term measures are needed until all issues concerning foreign labour recruitment can be resolved.

Six were killed on a highway after they escaped, including two children.

Fishermen reported the incident after finding six survivors not far from the coast.

Eighteen migrants are believed to still be missing, and authorities have deployed boats and an aircraft to hunt for them.