Mexico's Communications and Transport Ministry said on Tuesday it had taken over a concession to a southern railroad, whose trains are known locally as "The Beast," which thousands of Central American migrants have used to hitch rides to the United States.

The ministry scrapped the concession, which had belonged to the Ferrocarriles Chiapas-Mayab rail company, on the grounds of "public interest, public usage and national security," it said in a statement, without elaborating.

Ferrocarriles Chiapas-Mayab had been trying to wash its hands of the concession since at least 2007, according to a more-detailed account in the official government gazette.

The Chiapas-Mayab railroad, which has suffered from chronic underinvestment, begins in the southern state of Chiapas and connects with a network of freight trains that head northward.

For years, Central American migrants headed for the United States have illegally used "La Bestia," or "The Beast," to travel through Mexico.

However, after a surge in the number of U.S.-bound child migrants in 2014, Mexico clamped down, making it harder for migrants to jump aboard the freight train.

Officials said images of migrants riding on top of the trains, which were hotbeds of criminal activity, were a major embarrassment to Mexico internationally.

The flow of migrants now atop the trains is down about 90 percent from 2014 levels, officials said.

Two years ago, Mexico had said it would invest over six billion pesos ($326.44 million) to triple the speed of the trains, double cargo capacity and slash the number of accidents along the 413 miles of track due to be renovated.

Ferrocarriles Chiapas-Mayab was granted the concession in 1999 and its title was modified in 2012, the ministry said.

($1 = 18.3800 Mexican pesos)

(Reporting by Gabriel Stargardter, editing by G Crosse)

http://www.reuters.com/article/us-mexico-rail-migrants-idUSKCN10Y1ZR