Gunmen have stormed a rehab centre in a city on the frontline of Mexico's drug war, shooting dead at least 10 people and critically wounding two others, police said on Wednesday.

The shooting late on Tuesday was the second of its kind this month in Ciudad Juarez, the epicentre of Mexico's spiralling drug cartel violence where more than 1200 people have been killed this year alone.

Two weeks ago gunmen lined up 18 people and executed them at another drug treatment clinic in the city, which lies across the border from El Paso, Texas and is a key drug transit point.

Some 8500 soldiers have been deployed across this city of 1.4 million people to stem violence as cartels vie for control of lucrative smuggling routes and dominance of the local narcotics market.

The Mexican government has deployed tens of thousands of soldiers across the country to help quell drug-related violence, which has left some 10 000 people dead since 2008.