Mexican authorities are struggling to contain rising drug-related violence in border cities [AFP]

At least 25 people have been killed in a series of drug-related attacks in Ciudad Juarez, marking it the deadliest incident in more than two years for the Mexican border city.

Thursday's attacks in Ciudad Juarez included 15 people killed when attackers stormed four homes in three hours, according to Arturo Sandoval, a spokesman for the Attorney General's Office of Chihuahua state, where Ciudad Juarez is located.

In the worst of those attacks, armed men burst into a house and killed two young men - then killed four others for being witnesses.

Sandoval said it was the highest single-day murder toll in the city across from El Paso, Texas, since March 2008.

Two graffiti messages appeared in Ciudad Juarez threatening Joaquin "El Chapo" Guzman, the fugitive head of the Sinaloa drug cartel.

"You are killing our sons. You already did, and now we are going to kill your families," one sign read.

US drug consumption

Violence has continued unabated despite the deployment of thousands of soldiers to the city this year.

Federal police, including a special investigative unit, later took over security in the city as part of a new strategy announced by President Felipe Calderon.

More than 2,100 people have been killed this year in Ciudad Juarez, putting the city on pace to surpass its previous high of 2,700, set last year.

Despite the violence, Calderon disputed a statement made by last week by US secretary of state Hillary Clinton saying Mexico resembled Colombia two decades ago.

"These kind of comments like the ones made by secretary of state Clinton ... so careless, so lacking in seriousness, are very painful for Mexico, because they damage Mexico's image terribly," Calderon told local television.

"I think the main thing we have in common with Colombia is that both of our countries suffer from US drug consumption," Calderon said.

"We are both victims of the enormous American consumption of drugs, and now the sales of weapons."

Source: Agencies