MEXICO CITY (Reuters) - Vicente Fox, the former Mexican president who was a key U.S. ally in the war on drugs, has backed the legalization of drugs, saying prohibition has failed to curb Mexico’s spiraling violence and corruption.

Fox, whose successor Felipe Calderon is mired in a bloody military campaign against powerful drug cartels, criticized the government’s anti-drugs strategy on his blog, joining the ranks of other Latin American leaders who say the war on drugs is fundamentally flawed.

“Legalization does not mean that drugs are good ... but we have to see (legalization of the production, sale and distribution of drugs) as a strategy to weaken and break the economic system that allows cartels to earn huge profits,” Fox wrote in a posting over the weekend.

“Radical prohibition strategies have never worked.”

Violence is escalating in Mexico, where cartels earn billions of dollars a year as they battle for lucrative routes smuggling cocaine, marijuana, methamphetamine and other illegal drugs into the United States.

An estimated 28,000 people have died since late 2006, when Calderon sent soldiers and police across the country to battle drug gangs. The United States is funneling hundreds of millions of dollars into beefing up Mexico’s ability to chase cartels.

Yet there are few signs Mexico has turned the corner on what may be the defining issue of Calderon’s presidency. Many Mexicans now fear violence could deter business and investment, especially if it becomes more generalized.

“Although we know that many of the deaths are criminals killed by their rivals, unfortunately there are also officials, police and innocent people who have died,” Fox said.

He suggested the army, which has been accused of rights abuses as they go after drug suspects across Mexico, should return to the barracks.

“They are not prepared for police work,” Fox wrote.

While Calderon, like Fox a member of the conservative PAN party, opposes legalizing drugs, he has said that he supports a public debate on the issue. Since leaving office in 2006, Fox is seen as having little political influence in Mexico.

The pro-legalization position aligns Fox, once a close collaborator with former U.S. President George W. Bush, with other Latin American politicians seeking to reframe the “war on drugs” first declared by U.S-President Richard Nixon in 1971.

“Prohibitionist policies based on eradication, interdiction and criminalization of consumption simply haven’t worked,” Fernando Henrique Cardoso, Cesar Gaviria and Ernesto Zedillo, the former presidents of Brazil, Colombia and Mexico, wrote in a Wall Street Journal editorial last year.