Mexican federal police rescued 228 Central American migrants smuggled into the country inside a tractor trailer, the Ministry of Security and Citizen Protection said on Monday.

Officers stopped the cargo vehicle on a road in southern Chiapas state, next to the Guatemala border, during a routine inspection. After discovering the migrants, both the driver and his assistant were arrested.

The migrants from Honduras, El Salvador and Guatemala were crammed inside the trailer, used for transporting soda drinks, received medical attention and were handed over to immigration authorities.

Mexico has stepped up border security as part of an agreement recently reached with the U.S. to curb the sudden rise in undocumented migrants heading north.

Additional 200 migrants hidden in trucks have been captured by Mexican officials over the past two days. Dozens hidden and huddled together in secret compartments were detected by a large X-ray scanner.

Footage of the X-ray, revealed on Sunday, shows a ghost-like truck filled with the brightened silhouettes of the migrants, some sitting and others lying down, along two levels of the crowded compartments.

The apprehensions come weeks after the appointment of hard-charging former prisons chief, Francisco Garduno, as the new head of Mexico's immigration authority, the National Migration Institute (INM). Under Garduno, the agency has made a number of high-profile captures of migrants smuggled in commercial vehicles. The weekend Garduno took office, INM found 800 people in four trucks in the eastern state of Veracruz

Mexico's stepped-up efforts to stop record flows of mainly Guatemalans, Hondurans and El Salvadorans reaching the U.S., following a June 7 deal under which Mexico averted tariffs threatened by U.S. President Donald Trump with a promise to use security forces to intercept more undocumented migrants.

(With input from Reuters and Xinhua)