With 958 killings, March 2010 was Mexico's "bloodiest month" ever since President Felipe Calderon launched a military operation against the drug cartels in December 2006, a media report has said.
The figure brings the total number of gangland killings during the Calderon administration to 18,757, El Universal newspaper said on Thursday.
More than 2,550 people have died so far this year.
Chihuahua state in the northern border accounted for the majority of deaths -- 670 -- with the state's largest city, Ciudad Juarez, being termed Mexico's "murder capital".
Calderon, however, had said on Tuesday the media is exaggerating the violence in the country.
The president cited data indicating that Mexico suffers 11.5 homicides for every 100,000 inhabitants, "a high and worrisome number", but below the figures for Jamaica (67), the Dominican Republic (50) and Brazil, where the rate is 22 murders per 100,000 residents.
Brazil's relatively high murder rate, however, did not prevent the country from winning the right to host the 2014 soccer world cup or the 2016 Summer Olympics, Calderon said.
While acknowledging that some Mexican cities suffer from high levels of violence, the president said that others were at par with "the best in Europe" in terms in public safety.
Vowing to crush the drug cartels, Calderon said the administration has deployed 50,000 soldiers and 20,000 Federal Police officers in Mexico's roughest areas, yet the pace of killings has only accelerated, surging from 2,700 in 2007 to 7,724 last year.