It also comes as the US is to announce plans to dispatch more federal agents to its 3,000km border with Mexico in a bid to combat drug cartel operations in the region.

Hillary Clinton, the US secretary of state, is due to visit Mexico on Wednesday, followed by Janet Napolitano, the US homeland security secretary, and Eric Holder, the US attorney general.
 
Barack Obama, the US president, is also due to hold talks with Felipe Calderon, his Mexican counterpart, on April 16 and 17.

Bloody violence

At least 6,000 people died in drug-related violence in Mexico in 2008 and the number of deaths in 2009 has already reached 1,000, the Mexican government has estimated.

Calderon declared tough action against the country's drugs gangs shortly after entering office in 2006, sending thousands of troops to the volatile border regions, a move which sparked an explosion of violence from the drugs cartels.
 
Obama said earlier this month that the government was considering deploying the National Guard to the border to prevent violence crossing the border into the US.

Last month the governor of the US border state of Texas asked Obama to deploy 1,000 soldiers as a precaution, AFP reported.