MEXICO CITY (AP) - Mexican federal police say they have seized more than nine tonnes of marijuana, 168kg of crystal meth and a large cache of weapons this week in a northern border city caught in a bloody turf war between two drug cartels.

A Friday statement says a citizen's complaint led officers to two underground warehouses near a highway that links Monterrey with Reynosa, a city across the border from McAllen, Texas.

Police found five tonnes of marijuana and the crystal meth in one warehouse and 20 automatic rifles, thousands of bullets, 10 bulletproof vests, 20 uniforms, radios and tire spikes in the other.

Authorities didn't say where the other four tonnes of marijuana were found or what drug cartel owned the weapons and drugs.