Drug-related violence in Mexico increasingly has the hallmarks of an insurgency, US Secretary of State Hillary Clinton has said.
The recent use of car bombs by drug cartels was one indication, she said, adding, "It's looking more and more like Colombia looked 20 years ago."
Her comments were made following a major speech to US foreign policy experts in Washington.
A Mexican government spokesman rejected Mrs Clinton's analogy.
Speaking in Mexico City, Alejandro Poire said the only aspect that the Mexican and Colombian conflicts share is their root cause - a high demand for drugs in the US.
Mr Poire also denied that the presence of drug cartels was tantamount to an insurgency, insisting that "all the efforts of the Mexican state were going into fighting criminals"."
"The violence in Mexico was beginning to resemble Colombia of 20 years ago where insurgent groups at one time or another controlled some 40% of the country, Mrs Clinton added."
"More than 28,000 people have died in drug-related violence in Mexico since President Felipe Calderon deployed the army to fight the cartels in 2006 and violence has spilled over into Central America."