Mexico had the second-highest number of murders last year among countries considered in “armed conflict,” more than Iraq and Afghanistan, according to a report published on Tuesday that dealt a blow to President Enrique Pena Nieto's efforts to end a deadly drug war.

With nearly 23,000 intentional homicides in 2016, Mexico's murder tally was second only to war-torn Syria's 60,000, said Antonio Sampaio, one of the authors of the International Institute for Strategic Studies' “Armed Conflict Survey 2017.”

Iraq had roughly 17,000 murders, while Afghanistan had 16,000 last year, he added, noting that Mexico's militarised drug battle increasingly resembles an armed conflict.

Although the 2016 homicide data has been around for a few months, the revelation that Mexico's murder tally was second only to Syria's is a massive setback for Pena Nieto, who is struggling with tense negotiations with the administration of U.S. President Donald Trump, rising inflation and low approval ratings.

Pena Nieto's office did not immediately respond to a request for comment.

While homicides are generally reported at a rate per 100,000 people, Sampaio said many countries in armed conflict lack reliable population data.

“We think absolute numbers are a good way of measuring intensity,” he said. “Plus 23,000 is a huge number; no doubt about that.”

Mexico City: Capital of Latin America Show all 4 1 /4 Mexico City: Capital of Latin America Mexico City: Capital of Latin America Bellas Artes Palace, Mexico City Eduardo Verdugo/AP Mexico City: Capital of Latin America Children dressed in traditional Mexican clothes pose for a photograph after a procession in honour of Saint Cecilia, in Mexico City Alexandre Meneghini/AP Mexico City: Capital of Latin America Mexican dancers clad as natives perform during the annual celebration of Our Lady of Guadalupe held at the Basilica of Guadalupe in Mexico City Ronaldo Schemidt/AFP Mexico City: Capital of Latin America Tourists travel in boats on the waters of the popular Xochimilco, southern Mexico City Jorge Gutierrez/EPA

Since taking office in 2012, Pena Nieto has sought to cast Mexico's as a modern economy, pushing through energy, telecommunications and labor laws aimed at kick-starting growth.

Nonetheless, his administration has been scarred by stubbornly weak growth, a perception of corruption and confused tactics on how to end a decade of drug violence that has killed well over 100,000 people.

The 2016 murder tally rose to its highest level since Pena Nieto became president, and the first few months of 2017 have shown no signs that the violence has stopped.

In January, Reuters reported that Mexico's declining security budget could help drive the 2017 murder tally to its highest level ever.

“The inability of the Mexican economy to grow by significant rates ... is a reason why the state is incapable of implementing a nationwide, significant security strategy to the same level that other Latin American countries have,” Sampaio said.

A split within the Sinaloa cartel, which was run by kingpin Joaquin “Chapo” Guzman until his arrest last year, and the continued ascent of fearsome newcomers the Jalisco New Generation cartel, also contributed to the rise, Sampaio said.