Mexico City  - Mexican authorities found a tunnel that was allegedly used for drug trafficking in the northern Mexican town of Agua Prieta on the US border, the Mexican public prosecutor's office said Wednesday.

Federal agents found the entrance to the 25-metre-long tunnel, with a 60-centimetre diameter, on the wall of a drainage pipe.

No one was arrested and the tunnel was closed off with cement.

Agua Prieta is across the border from Douglas, in the US state of Arizona. (dpa)