MEXICO CITY (AFP) - US Secretary of Homeland Security John Kelly met Mexican President Enrique Pena Nieto on Wednesday (July 5) to discuss the countries' joint fight against drug cartels, officials said.

Mr Kelly arrived in Mexico on Wednesday for three days of high-level talks on trade and security ahead of a meeting between the US and Mexican presidents.

He and Mr Pena Nieto "emphasised the importance that both countries' authorities continue working jointly to fight transnational organised crime, based on the shared responsibility that both nations have recognised", said a statement from the Mexican President's office.

Supplying narcotics to the United States is a multibillion-dollar business for Mexico's drug cartels, whose grisly violence and heavy artillery have turned into a security headache for both countries.

At least 14 people died on Wednesday in a huge shootout between police and two rival drug gangs in northern Mexico, the authorities said.

The pre-dawn shootout near the remote town of Las Varas started as a firefight between rival drug trafficking gangs, then escalated when police arrived, said Mr Eduardo Esparza of the prosecutor's office for the state of Chihuahua, which borders the United States.

The region is hotly disputed territory for Mexico's drug cartels because its mountainous terrain and proximity to the border make it a strategic corridor for shipping narcotics to the US.

Investigators believe the groups involved in the shootout were "La Linea" - the armed wing of the Juarez cartel - and hitmen from the powerful Sinaloa cartel, Mr Esparza told AFP.

Both groups opened fire on officers when they arrived on the scene, said state police chief Oscar Aparicio.

"We can't rule out that there are more people dead. It was a very intense confrontation. There were more than 60 (gunmen)," he told Mexican radio network Formula.

It was the latest in a series of deadly clashes between police, rival drug gangs and warring factions within the Sinaloa cartel, which has been in turmoil since its kingpin Joaquin "El Chapo" Guzman was extradited to the United States in January.

Last Friday, 17 gunmen were killed in a spectacular shootout with police on a highway in Sinaloa, the north-western state that is the Guzman cartel's home base.

May was the deadliest month in Mexico since the government began keeping track in 1997, with 2,186 homicides.

Mr Kelly's visit comes at a tense time in US-Mexican relations, which have been strained by President Donald Trump's planned border wall, his attacks on Mexican immigrants as "criminals, drug dealers and rapists", and his insistence on holding tough new trade negotiations.

This is Mr Kelly's second official trip to Mexico. He first visited in February with Secretary of State Rex Tillerson, just weeks after Mr Trump's inauguration.

On that trip, Mr Kelly promised there would be no mass deportation of undocumented Mexicans living in the United States as Mr Trump had suggested.

Mr Trump and Mr Pena Nieto are scheduled to meet on Friday on the sidelines of the Group of 20 (G-20) summit in Hamburg, Germany.

The sit-down comes five months after the first official meeting between the two leaders was aborted in a diplomatic spat.

Mexico is not expecting much improvement in neighbourly relations to emerge from the presidents' meeting, Mexican Foreign Minister Luis Videgaray said on Wednesday.

"We're not expecting any major agreements, we're not expecting to settle substantive differences," he told Mexican TV network Televisa.