Mexican youth scale US border

SONORA, MEXICO (REUTERS) - A Mexican news channel was filming on the Arizona side of the border, when the camera crew spotted this: two young men climbing down into US territory from Sonora, a Mexican state known for drug crime.

The pair are undetected by US border patrol officers.

One of them carries a walkie-talkie.

It's unclear what their backpacks contained, and when this footage was shot.

Shortly afterwards, they clambered over the fence again back into Mexico.

The release of the video comes amid heated campaigning for the Republican primaries in the United States.

Controversial front runner Donald Trump has vowed to build a wall spanning the international border to stop the flow of illegal migrants and drugs.

Mexico says such a move would be bad for trade and the environment.

About a third of the 3,000km border between the countries is fenced, and this barrier in Arizona is one of the most complete.