A Mexican citizen working for a farm-labor arm of the AFL-CIO labor union has been found murdered in the group's offices in Monterrey, Mexico.

The US-based Farm Labor Organizing Committee announced the murder, saying Santiago Rafael Cruz was apparently tied up and beaten to death before he was found on Monday in the Mexican office.

The labor group works to help Mexicans get visas to work in the United States and tries to ensure they are treated fairly. In a statement, the group said Santiago spent years defending his countrymen's rights in the United States and Mexico.

The organization said it has asked US officials to press Mexico for a thorough investigation.

The Farm Labor Organizing Committee said it has dealt with countless attacks in both the United States and Mexico, including harassment of staff members and office burglaries. The group said this murder does not appear to be linked to a burglary because nothing was missing from the office.

Some information for this report was provided by AFP, AP and Reuters.